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/gitea.py

@@ -162,7 +162,7 @@ async def get_labels(request: Request, owner: str, repo: str):
 # ── Account linking ──
 
 @router.get("/status")
-async def gitea_status(request: Request):
+def gitea_status(request: Request):
     """Check if the current user has Gitea linked."""
     from app.services.gitea_client import get_user_gitea_client
     client = get_user_gitea_client(request)
@@ -170,7 +170,7 @@ async def gitea_status(request: Request):
 
 
 @router.delete("/disconnect")
-async def disconnect_gitea(request: Request):
+def disconnect_gitea(request: Request):
     """Remove all Gitea OAuth tokens for the current user."""
     from app.auth.session import SessionManager
     from app.db import get_conn
@@ -186,7 +186,7 @@ async def disconnect_gitea(request: Request):
 # ── Private Pages (local FlowDeck pages linked to Gitea project) ──
 
 @router.get("/projects/{owner}/{repo}/private-pages")
-async def list_private_pages(owner: str, repo: str, request: Request):
+def list_private_pages(owner: str, repo: str, request: Request):
     """List private pages for this Gitea project."""
     from app.auth.session import SessionManager
     from app.db import get_conn
@@ -225,7 +225,7 @@ async def create_private_page(owner: str, repo: str, request: Request):
 
 
 @router.get("/projects/{owner}/{repo}/private-pages/{page_id}")
-async def get_private_page(owner: str, repo: str, page_id: int, request: Request):
+def get_private_page(owner: str, repo: str, page_id: int, request: Request):
     """Get a single private page."""
     from app.auth.session import SessionManager
     from app.db import get_conn
@@ -272,7 +272,7 @@ async def update_private_page(owner: str, repo: str, page_id: int, request: Requ
 
 
 @router.delete("/projects/{owner}/{repo}/private-pages/{page_id}")
-async def delete_private_page(owner: str, repo: str, page_id: int, request: Request):
+def delete_private_page(owner: str, repo: str, page_id: int, request: Request):
     """Delete a private page."""
     from app.auth.session import SessionManager
     from app.db import get_conn