fix: A21 phase 1 — 352 routes async sans await → threadpool (v7.8.0)

- Conversion `async def` → `def` de TOUTES les routes dont le corps ne contient
  ni `await`, ni `async with`, ni `async for`, ni `asyncio` (scan automatique
  corps par corps sur app/ : 352 converties, 0 dangereuses, vérifié
  `asyncio`/`run_coroutine`/`.result()` absents). FastAPI exécute ces handlers
  dans son threadpool → tout leur SQLite (`get_conn()` + `conn.execute`) quitte
  l'event loop, sans changer une ligne de logique.
- Répartition : api_v2 60, dashboard 40, collections 25, board 23,
  workspace 19, wiki 17, permissions 14, api 14, main.py 6, + 35 fichiers.
- Les 4 routers prioritaires de l'audit sont couverts par ce lot :
  api_v2 60 + dashboard 40 + collections 25 + board 23 = 148 conversions
  (le reste de leurs routes attend la phase 2 : elles ont de vrais `await`).
- Reste (phase 2) : les 311 routes avec de vrais `await` → enrouler les blocs
  DB dans `await anyio.to_thread.run_sync(...)` ; pas de wrapper partagé livré
  (rien ne l'appellerait — YAGNI jusqu'au premier usage).

suite **1037/1037** (233 s) · `ruff check app tests` OK · docs à jour

app/routers/library.py

@@ -157,7 +157,7 @@ BASE_SELECT = (
 
 
 @router.get("/recents")
-async def library_recents(
+def library_recents(
     request: Request,
     source_type: str = Query(default="all"),
     tree: int = Query(default=0),
@@ -191,7 +191,7 @@ async def library_recents(
 
 
 @router.get("/favorites")
-async def library_favorites(
+def library_favorites(
     request: Request,
     source_type: str = Query(default="all"),
     tree: int = Query(default=0),
@@ -221,7 +221,7 @@ async def library_favorites(
 
 
 @router.get("/shared")
-async def library_shared(
+def library_shared(
     request: Request,
     source_type: str = Query(default="all"),
     tree: int = Query(default=0),
@@ -292,7 +292,7 @@ async def library_shared(
 
 
 @router.get("/published")
-async def library_published(
+def library_published(
     request: Request,
     source_type: str = Query(default="all"),
     tree: int = Query(default=0),
@@ -317,7 +317,7 @@ async def library_published(
 
 
 @router.get("/private")
-async def library_private(
+def library_private(
     request: Request,
     source_type: str = Query(default="all"),
     tree: int = Query(default=0),
@@ -342,7 +342,7 @@ async def library_private(
 
 
 @router.get("/local-workspace-children/{item_id:int}")
-async def library_local_workspace_children(item_id: int, request: Request):
+def library_local_workspace_children(item_id: int, request: Request):
     """Return children of a local workspace item for tree expansion."""
     _get_user_id(request)
     with get_conn() as conn:
@@ -410,7 +410,7 @@ async def library_local_workspace_children(item_id: int, request: Request):
 
 
 @router.get("/children/{page_id:int}")
-async def library_children(page_id: int, request: Request):
+def library_children(page_id: int, request: Request):
     """Return child pages for a given parent page (for tree expansion in Library)."""
     uid = _get_user_id(request)
     with get_conn() as conn:
@@ -426,7 +426,7 @@ async def library_children(page_id: int, request: Request):
 
 
 @router.get("/repository")
-async def library_repository(
+def library_repository(
     request: Request,
     gitea_owner: str = Query(default=""),
     gitea_repo: str = Query(default=""),
@@ -450,7 +450,7 @@ async def library_repository(
 
 
 @router.get("/local-workspace")
-async def library_local_workspace(
+def library_local_workspace(
     request: Request,
     workspace_id: int = Query(default=0),
 ):
@@ -535,7 +535,7 @@ def _format_size(size_bytes):
 
 
 @router.get("/workspace")
-async def library_workspace(
+def library_workspace(
     request: Request,
     source_type: str = Query(default="all"),
     tree: int = Query(default=0),