feat: conversion CBR → CBZ via job asynchrone

Ajoute la possibilité de convertir un livre CBR en CBZ depuis le backoffice.
La conversion est sécurisée : le CBR original n'est supprimé qu'après vérification
du CBZ généré et mise à jour de la base de données.

- parsers: nouvelle fn `convert_cbr_to_cbz` (unar extract → zip pack → vérification → rename atomique)
- api: `POST /books/:id/convert` crée un job `cbr_to_cbz` (vérifie format CBR, détecte collision)
- indexer: nouveau `converter.rs` dispatché depuis `job.rs`
- backoffice: bouton "Convert to CBZ" sur la page détail (visible si CBR), label dans JobRow
- migrations: colonne `book_id` sur `index_jobs` + type `cbr_to_cbz` dans le check constraint

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

apps/backoffice/app/api/books/[bookId]/convert/route.ts

@@ -0,0 +1,17 @@
+import { NextRequest, NextResponse } from "next/server";
+import { convertBook } from "@/lib/api";
+
+export async function POST(
+  _request: NextRequest,
+  { params }: { params: Promise<{ bookId: string }> }
+) {
+  const { bookId } = await params;
+  try {
+    const data = await convertBook(bookId);
+    return NextResponse.json(data);
+  } catch (error) {
+    const message = error instanceof Error ? error.message : "Failed to start conversion";
+    const status = message.includes("409") ? 409 : 500;
+    return NextResponse.json({ error: message }, { status });
+  }
+}

apps/backoffice/app/books/[id]/page.tsx

@@ -1,5 +1,6 @@
 import { fetchLibraries, getBookCoverUrl, BookDto, apiFetch } from "../../../lib/api";
 import { BookPreview } from "../../components/BookPreview";
+import { ConvertButton } from "../../components/ConvertButton";
 import Image from "next/image";
 import Link from "next/link";
 import { notFound } from "next/navigation";
@@ -115,7 +116,10 @@ export default async function BookDetailPage({
               {book.file_format && (
                 <div className="flex items-center justify-between py-2 border-b border-border">
                   <span className="text-sm text-muted-foreground">File Format:</span>
-                  <span className="text-sm text-foreground">{book.file_format.toUpperCase()}</span>
+                  <div className="flex items-center gap-3">
+                    <span className="text-sm text-foreground">{book.file_format.toUpperCase()}</span>
+                    {book.file_format === "cbr" && <ConvertButton bookId={book.id} />}
+                  </div>
                 </div>
               )}
 

apps/backoffice/app/components/ConvertButton.tsx

@@ -0,0 +1,71 @@
+"use client";
+
+import { useState } from "react";
+import Link from "next/link";
+import { Button } from "./ui";
+
+interface ConvertButtonProps {
+  bookId: string;
+}
+
+type ConvertState =
+  | { type: "idle" }
+  | { type: "loading" }
+  | { type: "success"; jobId: string }
+  | { type: "error"; message: string };
+
+export function ConvertButton({ bookId }: ConvertButtonProps) {
+  const [state, setState] = useState<ConvertState>({ type: "idle" });
+
+  const handleConvert = async () => {
+    setState({ type: "loading" });
+    try {
+      const res = await fetch(`/api/books/${bookId}/convert`, { method: "POST" });
+      if (!res.ok) {
+        const body = await res.json().catch(() => ({ error: res.statusText }));
+        setState({ type: "error", message: body.error || "Conversion failed" });
+        return;
+      }
+      const job = await res.json();
+      setState({ type: "success", jobId: job.id });
+    } catch (err) {
+      setState({ type: "error", message: err instanceof Error ? err.message : "Unknown error" });
+    }
+  };
+
+  if (state.type === "success") {
+    return (
+      <div className="flex items-center gap-2 text-sm text-success">
+        <span>Conversion started.</span>
+        <Link href={`/jobs/${state.jobId}`} className="text-primary hover:underline font-medium">
+          View job →
+        </Link>
+      </div>
+    );
+  }
+
+  if (state.type === "error") {
+    return (
+      <div className="flex flex-col gap-1">
+        <span className="text-sm text-destructive">{state.message}</span>
+        <button
+          className="text-xs text-muted-foreground hover:underline text-left"
+          onClick={() => setState({ type: "idle" })}
+        >
+          Dismiss
+        </button>
+      </div>
+    );
+  }
+
+  return (
+    <Button
+      variant="secondary"
+      size="sm"
+      onClick={handleConvert}
+      disabled={state.type === "loading"}
+    >
+      {state.type === "loading" ? "Converting…" : "Convert to CBZ"}
+    </Button>
+  );
+}

apps/backoffice/app/components/JobRow.tsx

@@ -93,7 +93,9 @@ export function JobRow({ job, libraryName, highlighted, onCancel, formatDate, fo
         <td className="px-4 py-3 text-sm text-foreground">
           {job.library_id ? libraryName || job.library_id.slice(0, 8) : "—"}
         </td>
-        <td className="px-4 py-3 text-sm text-foreground">{job.type}</td>
+        <td className="px-4 py-3 text-sm text-foreground">
+          {job.type === "cbr_to_cbz" ? "CBR → CBZ" : job.type}
+        </td>
         <td className="px-4 py-3">
           <div className="flex items-center gap-2 flex-wrap">
             <StatusBadge status={job.status} />