feat: multi-user reading progress & backoffice impersonation

- Scope all reading progress (books, series, stats) by user via
  Option<Extension<AuthUser>> — admin sees aggregate, read token sees own data
- Fix duplicate book rows when admin views lists (IS NOT NULL guard on JOIN)
- Add X-As-User header support: admin can impersonate any user from backoffice
- UserSwitcher dropdown in nav header (persisted via as_user_id cookie)
- Per-user filter pills on "Currently reading" and "Recently read" dashboard sections
- Inline username editing (UsernameEdit component with optimistic update)
- PATCH /admin/users/:id endpoint to rename a user
- Unassigned read tokens row in users table
- Komga sync now requires a user_id — reading progress attributed to selected user
- Migration 0051: add user_id column to komga_sync_reports
- Nav breakpoints: icons-only from md, labels from xl, hamburger until md

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/backoffice/app/(app)/tokens/page.tsx

@@ -1,7 +1,9 @@
 import { revalidatePath } from "next/cache";
 import { redirect } from "next/navigation";
-import { listTokens, createToken, revokeToken, deleteToken, TokenDto } from "@/lib/api";
+import { listTokens, createToken, revokeToken, deleteToken, updateToken, fetchUsers, createUser, deleteUser, updateUser, TokenDto, UserDto } from "@/lib/api";
 import { Card, CardHeader, CardTitle, CardDescription, CardContent, Button, Badge, FormField, FormInput, FormSelect, FormRow } from "@/app/components/ui";
+import { TokenUserSelect } from "@/app/components/TokenUserSelect";
+import { UsernameEdit } from "@/app/components/UsernameEdit";
 import { getServerTranslations } from "@/lib/i18n/server";
 
 export const dynamic = "force-dynamic";
@@ -14,13 +16,15 @@ export default async function TokensPage({
   const { t } = await getServerTranslations();
   const params = await searchParams;
   const tokens = await listTokens().catch(() => [] as TokenDto[]);
+  const users = await fetchUsers().catch(() => [] as UserDto[]);
 
   async function createTokenAction(formData: FormData) {
     "use server";
     const name = formData.get("name") as string;
     const scope = formData.get("scope") as string;
+    const userId = (formData.get("user_id") as string) || undefined;
     if (name) {
-      const result = await createToken(name, scope);
+      const result = await createToken(name, scope, userId);
       revalidatePath("/tokens");
       redirect(`/tokens?created=${encodeURIComponent(result.token)}`);
     }
@@ -40,6 +44,40 @@ export default async function TokensPage({
     revalidatePath("/tokens");
   }
 
+  async function createUserAction(formData: FormData) {
+    "use server";
+    const username = formData.get("username") as string;
+    if (username) {
+      await createUser(username);
+      revalidatePath("/tokens");
+    }
+  }
+
+  async function deleteUserAction(formData: FormData) {
+    "use server";
+    const id = formData.get("id") as string;
+    await deleteUser(id);
+    revalidatePath("/tokens");
+  }
+
+  async function renameUserAction(formData: FormData) {
+    "use server";
+    const id = formData.get("id") as string;
+    const username = formData.get("username") as string;
+    if (username?.trim()) {
+      await updateUser(id, username.trim());
+      revalidatePath("/tokens");
+    }
+  }
+
+  async function reassignTokenAction(formData: FormData) {
+    "use server";
+    const id = formData.get("id") as string;
+    const userId = (formData.get("user_id") as string) || null;
+    await updateToken(id, userId);
+    revalidatePath("/tokens");
+  }
+
   return (
     <>
       <div className="mb-6">
@@ -51,6 +89,115 @@ export default async function TokensPage({
         </h1>
       </div>
 
+      {/* ── Lecteurs ─────────────────────────────────────────── */}
+      <div className="mb-2">
+        <h2 className="text-xl font-semibold text-foreground">{t("users.title")}</h2>
+      </div>
+
+      <Card className="mb-6">
+        <CardHeader>
+          <CardTitle>{t("users.createNew")}</CardTitle>
+          <CardDescription>{t("users.createDescription")}</CardDescription>
+        </CardHeader>
+        <CardContent>
+          <form action={createUserAction}>
+            <FormRow>
+              <FormField className="flex-1 min-w-48">
+                <FormInput name="username" placeholder={t("users.username")} required autoComplete="off" />
+              </FormField>
+              <Button type="submit">{t("users.createButton")}</Button>
+            </FormRow>
+          </form>
+        </CardContent>
+      </Card>
+
+      <Card className="overflow-hidden mb-10">
+        <div className="overflow-x-auto">
+          <table className="w-full">
+            <thead>
+              <tr className="border-b border-border/60 bg-muted/50">
+                <th className="px-4 py-3 text-left text-xs font-semibold text-muted-foreground uppercase tracking-wider">{t("users.name")}</th>
+                <th className="px-4 py-3 text-left text-xs font-semibold text-muted-foreground uppercase tracking-wider">{t("users.tokenCount")}</th>
+                <th className="px-4 py-3 text-left text-xs font-semibold text-muted-foreground uppercase tracking-wider">{t("status.read")}</th>
+                <th className="px-4 py-3 text-left text-xs font-semibold text-muted-foreground uppercase tracking-wider">{t("status.reading")}</th>
+                <th className="px-4 py-3 text-left text-xs font-semibold text-muted-foreground uppercase tracking-wider">{t("users.createdAt")}</th>
+                <th className="px-4 py-3 text-left text-xs font-semibold text-muted-foreground uppercase tracking-wider">{t("users.actions")}</th>
+              </tr>
+            </thead>
+            <tbody className="divide-y divide-border/60">
+              {/* Ligne admin synthétique */}
+              <tr className="hover:bg-accent/50 transition-colors bg-destructive/5">
+                <td className="px-4 py-3 text-sm font-medium text-foreground flex items-center gap-2">
+                  {process.env.ADMIN_USERNAME ?? "admin"}
+                  <Badge variant="destructive">{t("tokens.scopeAdmin")}</Badge>
+                </td>
+                <td className="px-4 py-3 text-sm text-muted-foreground">
+                  {tokens.filter(tok => tok.scope === "admin" && !tok.revoked_at).length}
+                </td>
+                <td className="px-4 py-3 text-sm text-muted-foreground/50">—</td>
+                <td className="px-4 py-3 text-sm text-muted-foreground/50">—</td>
+                <td className="px-4 py-3 text-sm text-muted-foreground/50">—</td>
+                <td className="px-4 py-3 text-sm text-muted-foreground/50">—</td>
+              </tr>
+              {/* Ligne tokens read non assignés */}
+              {(() => {
+                const unassigned = tokens.filter(tok => tok.scope === "read" && !tok.user_id && !tok.revoked_at);
+                if (unassigned.length === 0) return null;
+                return (
+                  <tr className="hover:bg-accent/50 transition-colors bg-warning/5">
+                    <td className="px-4 py-3 text-sm font-medium text-muted-foreground italic">
+                      {t("tokens.noUser")}
+                    </td>
+                    <td className="px-4 py-3 text-sm text-warning font-medium">{unassigned.length}</td>
+                    <td className="px-4 py-3 text-sm text-muted-foreground/50">—</td>
+                    <td className="px-4 py-3 text-sm text-muted-foreground/50">—</td>
+                    <td className="px-4 py-3 text-sm text-muted-foreground/50">—</td>
+                    <td className="px-4 py-3 text-sm text-muted-foreground/50">—</td>
+                  </tr>
+                );
+              })()}
+              {users.map((user) => (
+                  <tr key={user.id} className="hover:bg-accent/50 transition-colors">
+                    <td className="px-4 py-3">
+                      <UsernameEdit userId={user.id} currentUsername={user.username} action={renameUserAction} />
+                    </td>
+                    <td className="px-4 py-3 text-sm text-muted-foreground">{user.token_count}</td>
+                    <td className="px-4 py-3 text-sm">
+                      {user.books_read > 0
+                        ? <span className="font-medium text-success">{user.books_read}</span>
+                        : <span className="text-muted-foreground/50">—</span>}
+                    </td>
+                    <td className="px-4 py-3 text-sm">
+                      {user.books_reading > 0
+                        ? <span className="font-medium text-amber-500">{user.books_reading}</span>
+                        : <span className="text-muted-foreground/50">—</span>}
+                    </td>
+                    <td className="px-4 py-3 text-sm text-muted-foreground">
+                      {new Date(user.created_at).toLocaleDateString()}
+                    </td>
+                    <td className="px-4 py-3">
+                      <form action={deleteUserAction}>
+                        <input type="hidden" name="id" value={user.id} />
+                        <Button type="submit" variant="destructive" size="sm">
+                          <svg className="w-4 h-4 mr-1" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                            <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M19 7l-.867 12.142A2 2 0 0116.138 21H7.862a2 2 0 01-1.995-1.858L5 7m5 4v6m4-6v6m1-10V4a1 1 0 00-1-1h-4a1 1 0 00-1 1v3M4 7h16" />
+                          </svg>
+                          {t("common.delete")}
+                        </Button>
+                      </form>
+                    </td>
+                  </tr>
+                ))}
+            </tbody>
+          </table>
+        </div>
+      </Card>
+
+      {/* ── Tokens API ───────────────────────────────────────── */}
+      <div className="mb-2">
+        <h2 className="text-xl font-semibold text-foreground">{t("tokens.apiTokens")}</h2>
+      </div>
+
       {params.created ? (
         <Card className="mb-6 border-success/50 bg-success/5">
           <CardHeader>
@@ -72,7 +219,7 @@ export default async function TokensPage({
           <form action={createTokenAction}>
             <FormRow>
               <FormField className="flex-1 min-w-48">
-                <FormInput name="name" placeholder={t("tokens.tokenName")} required />
+                <FormInput name="name" placeholder={t("tokens.tokenName")} required autoComplete="off" />
               </FormField>
               <FormField className="w-32">
                 <FormSelect name="scope" defaultValue="read">
@@ -80,6 +227,14 @@ export default async function TokensPage({
                   <option value="admin">{t("tokens.scopeAdmin")}</option>
                 </FormSelect>
               </FormField>
+              <FormField className="w-48">
+                <FormSelect name="user_id" defaultValue="">
+                  <option value="">{t("tokens.noUser")}</option>
+                  {users.map((user) => (
+                    <option key={user.id} value={user.id}>{user.username}</option>
+                  ))}
+                </FormSelect>
+              </FormField>
               <Button type="submit">{t("tokens.createButton")}</Button>
             </FormRow>
           </form>
@@ -92,6 +247,7 @@ export default async function TokensPage({
             <thead>
               <tr className="border-b border-border/60 bg-muted/50">
                 <th className="px-4 py-3 text-left text-xs font-semibold text-muted-foreground uppercase tracking-wider">{t("tokens.name")}</th>
+                <th className="px-4 py-3 text-left text-xs font-semibold text-muted-foreground uppercase tracking-wider">{t("tokens.user")}</th>
                 <th className="px-4 py-3 text-left text-xs font-semibold text-muted-foreground uppercase tracking-wider">{t("tokens.scope")}</th>
                 <th className="px-4 py-3 text-left text-xs font-semibold text-muted-foreground uppercase tracking-wider">{t("tokens.prefix")}</th>
                 <th className="px-4 py-3 text-left text-xs font-semibold text-muted-foreground uppercase tracking-wider">{t("tokens.status")}</th>
@@ -102,6 +258,15 @@ export default async function TokensPage({
               {tokens.map((token) => (
                 <tr key={token.id} className="hover:bg-accent/50 transition-colors">
                   <td className="px-4 py-3 text-sm text-foreground">{token.name}</td>
+                  <td className="px-4 py-3 text-sm">
+                    <TokenUserSelect
+                      tokenId={token.id}
+                      currentUserId={token.user_id}
+                      users={users}
+                      action={reassignTokenAction}
+                      noUserLabel={t("tokens.noUser")}
+                    />
+                  </td>
                   <td className="px-4 py-3 text-sm">
                     <Badge variant={token.scope === "admin" ? "destructive" : "secondary"}>
                       {token.scope}