feat: auto-téléchargement par catégorie avec souscription persistante

- Bouton ⬇ sur chaque pill de catégorie pour activer/désactiver l'auto-DL
- Souscriptions sauvegardées en SQLite (table auto_dl_categories)
- Boucle background toutes les AUTO_DL_INTERVAL secondes (défaut 1h)
- Déduplication via already_enqueued() (évite re-queue si déjà queued/done)
- POST /api/auto-dl/check pour déclencher un check immédiat
- GET/POST/DELETE /api/auto-dl/{category} pour gérer les souscriptions

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

downloader.py

@@ -1,3 +1,4 @@
+import asyncio
 import re
 import sqlite3
 import threading
@@ -103,11 +104,48 @@ class DownloadManager:
                     error    TEXT
                 )
             """)
+            conn.execute("""
+                CREATE TABLE IF NOT EXISTS auto_dl_categories (
+                    category TEXT PRIMARY KEY,
+                    added_at TEXT NOT NULL
+                )
+            """)
 
     # ------------------------------------------------------------------ public
 
-    def enqueue(self, url: str, title: str, subtitle: str, year: int | None,
-                category: str, bg: BackgroundTasks) -> str:
+    def get_watched_categories(self) -> list[str]:
+        with _db() as conn:
+            rows = conn.execute(
+                "SELECT category FROM auto_dl_categories ORDER BY added_at"
+            ).fetchall()
+        return [r["category"] for r in rows]
+
+    def watch_category(self, category: str):
+        with _db() as conn:
+            conn.execute(
+                "INSERT OR IGNORE INTO auto_dl_categories (category, added_at) VALUES (?,?)",
+                (category, datetime.now().isoformat()),
+            )
+
+    def unwatch_category(self, category: str):
+        with _db() as conn:
+            conn.execute("DELETE FROM auto_dl_categories WHERE category=?", (category,))
+
+    def already_enqueued(self, url: str) -> bool:
+        with _db() as conn:
+            row = conn.execute(
+                "SELECT id FROM downloads WHERE url=? AND state != 'error' LIMIT 1", (url,)
+            ).fetchone()
+        return row is not None
+
+    def already_downloaded(self, url: str) -> bool:
+        with _db() as conn:
+            row = conn.execute(
+                "SELECT id FROM downloads WHERE url=? AND state='done' LIMIT 1", (url,)
+            ).fetchone()
+        return row is not None
+
+    def _insert_queued(self, url: str, title: str) -> str:
         dl_id = str(uuid.uuid4())
         now = datetime.now().isoformat()
         with _db() as conn:
@@ -117,9 +155,21 @@ class DownloadManager:
             )
         with self._lock:
             self._active[dl_id] = {"state": "queued", "progress": 0, "title": title}
+        return dl_id
+
+    def enqueue(self, url: str, title: str, subtitle: str, year: int | None,
+                category: str, bg: BackgroundTasks) -> str:
+        dl_id = self._insert_queued(url, title)
         bg.add_task(self._run, dl_id, url, title, subtitle, year, category)
         return dl_id
 
+    async def enqueue_direct(self, url: str, title: str, subtitle: str,
+                             year: int | None, category: str) -> str:
+        dl_id = self._insert_queued(url, title)
+        loop = asyncio.get_running_loop()
+        loop.run_in_executor(None, self._run, dl_id, url, title, subtitle, year, category)
+        return dl_id
+
     def status(self, dl_id: str) -> dict:
         with self._lock:
             return dict(self._active.get(dl_id, {"state": "unknown"}))