refactor: Phase E — types de réponses API standardisés + SVGs inline → Icon

E1 - API responses:
- Crée responses.rs avec OkResponse, DeletedResponse, UpdatedResponse,
  RevokedResponse, UnlinkedResponse, StatusResponse (6 tests de sérialisation)
- Remplace ~15 json!() inline par des types structurés dans books, libraries,
  tokens, users, handlers, anilist, metadata, download_detection, torrent_import
- Signatures de retour des handlers typées (plus de serde_json::Value)

E2 - SVGs → Icon component:
- Ajoute icon "lock" au composant Icon
- Remplace ~30 SVGs inline par <Icon> dans 9 composants
  (FolderPicker, FolderBrowser, LiveSearchForm, JobRow, LibraryActions,
  ReadingStatusModal, EditBookForm, EditSeriesForm, UserSwitcher)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/backoffice/app/components/EditSeriesForm.tsx

@@ -4,6 +4,7 @@ import { useState, useTransition, useEffect, useCallback } from "react";
 import { Modal } from "./ui/Modal";
 import { useRouter } from "next/navigation";
 import { FormField, FormLabel, FormInput } from "./ui/Form";
+import { Icon } from "./ui";
 import { useTranslation } from "../../lib/i18n/context";
 
 function LockButton({
@@ -29,9 +30,7 @@ function LockButton({
       title={locked ? t("editBook.lockedField") : t("editBook.clickToLock")}
     >
       {locked ? (
-        <svg className="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
-          <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 15v2m-6 4h12a2 2 0 002-2v-6a2 2 0 00-2-2H6a2 2 0 00-2 2v6a2 2 0 002 2zm10-10V7a4 4 0 00-8 0v4h8z" />
-        </svg>
+        <Icon name="lock" size="sm" />
       ) : (
         <svg className="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
           <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M8 11V7a4 4 0 118 0m-4 8v2m-6 4h12a2 2 0 002-2v-6a2 2 0 00-2-2H6a2 2 0 00-2 2v6a2 2 0 002 2z" />
@@ -444,9 +443,7 @@ export function EditSeriesForm({
             {/* Lock legend */}
             {Object.values(lockedFields).some(Boolean) && (
               <p className="text-xs text-amber-500 flex items-center gap-1.5">
-                <svg className="w-3.5 h-3.5 shrink-0" fill="none" stroke="currentColor" viewBox="0 0 24 24">
-                  <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 15v2m-6 4h12a2 2 0 002-2v-6a2 2 0 00-2-2H6a2 2 0 00-2 2v6a2 2 0 002 2zm10-10V7a4 4 0 00-8 0v4h8z" />
-                </svg>
+                <Icon name="lock" size="sm" className="!w-3.5 !h-3.5 shrink-0" />
                 {t("editBook.lockedFieldsNote")}
               </p>
             )}