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/indexer/src/converter.rs

@@ -0,0 +1,108 @@
+use anyhow::Result;
+use sqlx::Row;
+use tracing::{info, warn};
+use uuid::Uuid;
+
+use crate::{utils, AppState};
+
+/// Execute a `cbr_to_cbz` job for the given `book_id`.
+///
+/// Flow:
+/// 1. Read book file info from DB
+/// 2. Resolve physical path
+/// 3. Convert CBR → CBZ via `parsers::convert_cbr_to_cbz`
+/// 4. Update `book_files` and `books` in DB
+/// 5. Delete the original CBR (failure here does not fail the job)
+/// 6. Mark job as success
+pub async fn convert_book(state: &AppState, job_id: Uuid, book_id: Uuid) -> Result<()> {
+    info!("[CONVERTER] Starting CBR→CBZ conversion for book {} (job {})", book_id, job_id);
+
+    // Fetch current file info
+    let row = sqlx::query(
+        r#"
+        SELECT bf.id as file_id, bf.abs_path, bf.format
+        FROM book_files bf
+        WHERE bf.book_id = $1
+        ORDER BY bf.updated_at DESC
+        LIMIT 1
+        "#,
+    )
+    .bind(book_id)
+    .fetch_optional(&state.pool)
+    .await?;
+
+    let row = row.ok_or_else(|| anyhow::anyhow!("no book file found for book {}", book_id))?;
+
+    let file_id: Uuid = row.get("file_id");
+    let abs_path: String = row.get("abs_path");
+    let format: String = row.get("format");
+
+    if format != "cbr" {
+        return Err(anyhow::anyhow!(
+            "book {} is not CBR (format={}), skipping conversion",
+            book_id,
+            format
+        ));
+    }
+
+    let physical_path = utils::remap_libraries_path(&abs_path);
+    let cbr_path = std::path::Path::new(&physical_path);
+
+    info!("[CONVERTER] Converting {} → CBZ", cbr_path.display());
+
+    // Update job status to running (already set by claim_next_job, this updates current_file)
+    sqlx::query(
+        "UPDATE index_jobs SET current_file = $2 WHERE id = $1",
+    )
+    .bind(job_id)
+    .bind(&abs_path)
+    .execute(&state.pool)
+    .await?;
+
+    // Do the conversion
+    let cbz_path = parsers::convert_cbr_to_cbz(cbr_path)?;
+
+    info!("[CONVERTER] CBZ created at {}", cbz_path.display());
+
+    // Remap physical path back to /libraries/ canonical form
+    let new_abs_path = utils::unmap_libraries_path(&cbz_path.to_string_lossy());
+
+    // Update book_files: abs_path + format
+    sqlx::query(
+        "UPDATE book_files SET abs_path = $2, format = 'cbz', updated_at = NOW() WHERE id = $1",
+    )
+    .bind(file_id)
+    .bind(&new_abs_path)
+    .execute(&state.pool)
+    .await?;
+
+    // Update books: kind stays 'comic', updated_at refreshed
+    sqlx::query("UPDATE books SET updated_at = NOW() WHERE id = $1")
+        .bind(book_id)
+        .execute(&state.pool)
+        .await?;
+
+    info!("[CONVERTER] DB updated for book {}", book_id);
+
+    // Delete the original CBR file (best-effort)
+    if let Err(e) = std::fs::remove_file(cbr_path) {
+        warn!(
+            "[CONVERTER] Could not delete original CBR {}: {} (non-fatal)",
+            cbr_path.display(),
+            e
+        );
+    } else {
+        info!("[CONVERTER] Deleted original CBR {}", cbr_path.display());
+    }
+
+    // Mark job success
+    sqlx::query(
+        "UPDATE index_jobs SET status = 'success', finished_at = NOW(), progress_percent = 100, current_file = NULL WHERE id = $1",
+    )
+    .bind(job_id)
+    .execute(&state.pool)
+    .await?;
+
+    info!("[CONVERTER] Job {} completed successfully", job_id);
+    Ok(())
+}