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/api.py

@@ -83,7 +83,7 @@ async def health(request: Request):
 
 
 @router.get("/stats")
-async def stats():
+def stats():
     """Global stats for dashboard."""
     with get_conn() as conn:
         board_count = conn.execute("SELECT COUNT(*) as c FROM boards").fetchone()["c"]
@@ -179,7 +179,7 @@ async def _get_status_labels(owner: str, repo: str, board_id: int) -> list[str]:
 
 
 @router.post("/col-mapping")
-async def set_col_mapping(
+def set_col_mapping(
     owner: str = Query(...),
     repo: str = Query(...),
     column: str = Query(...),
@@ -209,7 +209,7 @@ async def set_col_mapping(
 
 
 @router.delete("/col-mapping")
-async def delete_col_mapping(
+def delete_col_mapping(
     owner: str = Query(...),
     repo: str = Query(...),
     column: str = Query(...),
@@ -234,7 +234,7 @@ async def delete_col_mapping(
 
 
 @router.get("/board-config/{owner}/{repo}")
-async def get_board_config(owner: str, repo: str):
+def get_board_config(owner: str, repo: str):
     with get_conn() as conn:
         board = conn.execute(
             "SELECT * FROM boards WHERE project_owner=? AND project_name=?",
@@ -255,7 +255,7 @@ async def get_board_config(owner: str, repo: str):
 
 
 @router.post("/board-config/{owner}/{repo}")
-async def update_board_config(
+def update_board_config(
     owner: str,
     repo: str,
     columns: str = Query(default=""),
@@ -460,7 +460,7 @@ async def get_issue_detail(owner: str, repo: str, issue_id: int, format: str = Q
 # ── v0.5.0: Checklists ──
 
 @router.post("/checklists/{owner}/{repo}/{issue_id}")
-async def create_checklist(
+def create_checklist(
     owner: str,
     repo: str,
     issue_id: int,
@@ -484,7 +484,7 @@ async def create_checklist(
 
 
 @router.post("/checklist-items/{owner}/{repo}/{issue_id}/{checklist_id}")
-async def add_checklist_item(
+def add_checklist_item(
     owner: str,
     repo: str,
     issue_id: int,
@@ -502,7 +502,7 @@ async def add_checklist_item(
 
 
 @router.patch("/checklist-items/{item_id}")
-async def toggle_checklist_item(
+def toggle_checklist_item(
     item_id: int,
     checked: bool = Query(default=False),
     content: str = Query(default=""),
@@ -524,7 +524,7 @@ async def toggle_checklist_item(
 
 
 @router.delete("/checklist-items/{item_id}")
-async def delete_checklist_item(item_id: int):
+def delete_checklist_item(item_id: int):
     """Delete a checklist item."""
     with get_conn() as conn:
         conn.execute("DELETE FROM checklist_items WHERE id=?", (item_id,))
@@ -533,7 +533,7 @@ async def delete_checklist_item(item_id: int):
 
 
 @router.delete("/checklists/{checklist_id}")
-async def delete_checklist(checklist_id: int):
+def delete_checklist(checklist_id: int):
     """Delete a checklist and all its items."""
     with get_conn() as conn:
         conn.execute("DELETE FROM checklist_items WHERE checklist_id=?", (checklist_id,))
@@ -545,7 +545,7 @@ async def delete_checklist(checklist_id: int):
 # ── v1.0.0: User management ──
 
 @router.get("/users/me")
-async def get_my_profile(request: Request):
+def get_my_profile(request: Request):
     """Get current user profile."""
     user = SessionManager.decode_session(request.cookies.get("flowdeck_session", ""))
     if not user:
@@ -565,7 +565,7 @@ async def get_my_profile(request: Request):
 
 
 @router.put("/users/me")
-async def update_my_profile(request: Request, full_name: str = Query(default=""),
+def update_my_profile(request: Request, full_name: str = Query(default=""),
                              email: str = Query(default="")):
     """Update current user's local profile."""
     user = SessionManager.decode_session(request.cookies.get("flowdeck_session", ""))
@@ -584,7 +584,7 @@ async def update_my_profile(request: Request, full_name: str = Query(default="")
 # ── v0.5.0: Card priority & due date ──
 
 @router.post("/card/{owner}/{repo}/{issue_id}")
-async def update_card(
+def update_card(
     owner: str,
     repo: str,
     issue_id: int,
@@ -673,7 +673,7 @@ async def capture_frontend_error(request: Request):
 
 
 @router.get("/frontend-errors")
-async def get_frontend_errors(request: Request, clear: bool = True):
+def get_frontend_errors(request: Request, clear: bool = True):
     """Retourne les erreurs frontend récentes. Hermes appelle cette route."""
     errors = list(_frontend_errors)
     if clear: