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_v2_agent.py

@@ -103,7 +103,7 @@ def _engine_for(user_id: int, workspace_id: int | None, provider: str | None) ->
 # ── Agents ─────────────────────────────────────────────────────────────────
 
 @router.get("/agents")
-async def list_agents_v2(request: Request, authorization: str | None = Header(default=None)):
+def list_agents_v2(request: Request, authorization: str | None = Header(default=None)):
     user = _guard(request, authorization)
     limit, offset = parse_pagination(request)
     ws = _workspace_of(request)
@@ -157,7 +157,7 @@ async def create_agent_v2(request: Request, authorization: str | None = Header(d
 
 
 @router.get("/agents/{agent_id}")
-async def get_agent_v2(agent_id: int, request: Request, authorization: str | None = Header(default=None)):
+def get_agent_v2(agent_id: int, request: Request, authorization: str | None = Header(default=None)):
     _guard(request, authorization)
     with get_conn() as conn:
         row = conn.execute("SELECT * FROM agents WHERE id=?", (agent_id,)).fetchone()
@@ -195,7 +195,7 @@ async def update_agent_v2(agent_id: int, request: Request, authorization: str |
 
 
 @router.delete("/agents/{agent_id}")
-async def delete_agent_v2(agent_id: int, request: Request, authorization: str | None = Header(default=None)):
+def delete_agent_v2(agent_id: int, request: Request, authorization: str | None = Header(default=None)):
     user = _guard(request, authorization, write=True)
     with get_conn() as conn:
         if not conn.execute("SELECT id FROM agents WHERE id=?", (agent_id,)).fetchone():
@@ -209,7 +209,7 @@ async def delete_agent_v2(agent_id: int, request: Request, authorization: str |
 # ── Conversations (static paths declared before /agents/{agent_id}) ────────
 
 @router.get("/agents/conversations")
-async def list_conversations_v2(request: Request, authorization: str | None = Header(default=None)):
+def list_conversations_v2(request: Request, authorization: str | None = Header(default=None)):
     user = _guard(request, authorization)
     limit, offset = parse_pagination(request)
     with get_conn() as conn:
@@ -264,7 +264,7 @@ async def create_conversation_v2(request: Request, authorization: str | None = H
 
 
 @router.get("/agents/conversations/{conversation_id}")
-async def get_conversation_v2(conversation_id: int, request: Request,
+def get_conversation_v2(conversation_id: int, request: Request,
                               authorization: str | None = Header(default=None)):
     user = _guard(request, authorization)
     with get_conn() as conn:
@@ -279,7 +279,7 @@ async def get_conversation_v2(conversation_id: int, request: Request,
 
 
 @router.delete("/agents/conversations/{conversation_id}")
-async def delete_conversation_v2(conversation_id: int, request: Request,
+def delete_conversation_v2(conversation_id: int, request: Request,
                                  authorization: str | None = Header(default=None)):
     user = _guard(request, authorization, write=True)
     with get_conn() as conn:
@@ -292,7 +292,7 @@ async def delete_conversation_v2(conversation_id: int, request: Request,
 
 
 @router.get("/agents/conversations/{conversation_id}/actions")
-async def list_actions_v2(conversation_id: int, request: Request,
+def list_actions_v2(conversation_id: int, request: Request,
                           authorization: str | None = Header(default=None)):
     user = _guard(request, authorization)
     with get_conn() as conn:
@@ -306,7 +306,7 @@ async def list_actions_v2(conversation_id: int, request: Request,
 
 
 @router.post("/agents/actions/{action_id}/undo")
-async def undo_action_v2(action_id: int, request: Request,
+def undo_action_v2(action_id: int, request: Request,
                          authorization: str | None = Header(default=None)):
     user = _guard(request, authorization, write=True)
     with get_conn() as conn:
@@ -480,7 +480,7 @@ async def trigger_agent_v2(agent_id: int, request: Request,
 # ── Skill marketplace ──────────────────────────────────────────────────────
 
 @router.get("/skills")
-async def list_skills_v2(request: Request, authorization: str | None = Header(default=None)):
+def list_skills_v2(request: Request, authorization: str | None = Header(default=None)):
     _guard(request, authorization)
     limit, offset = parse_pagination(request)
     ws = _workspace_of(request)
@@ -535,7 +535,7 @@ async def create_skill_v2(request: Request, authorization: str | None = Header(d
 # Gallery & import are static segments: declared before /skills/{skill_id} so
 # FastAPI never tries to coerce "gallery" into an int path parameter.
 @router.get("/skills/gallery")
-async def skills_gallery_v2(request: Request, authorization: str | None = Header(default=None)):
+def skills_gallery_v2(request: Request, authorization: str | None = Header(default=None)):
     _guard(request, authorization)
     presets = skill_gallery.list_gallery()
     return {"gallery": presets, "total": len(presets),
@@ -596,7 +596,7 @@ async def import_skill_v2(request: Request, authorization: str | None = Header(d
 
 
 @router.get("/skills/{skill_id}")
-async def get_skill_v2(skill_id: int, request: Request, authorization: str | None = Header(default=None)):
+def get_skill_v2(skill_id: int, request: Request, authorization: str | None = Header(default=None)):
     _guard(request, authorization)
     with get_conn() as conn:
         row = conn.execute("SELECT * FROM agent_skills WHERE id=?", (skill_id,)).fetchone()
@@ -606,7 +606,7 @@ async def get_skill_v2(skill_id: int, request: Request, authorization: str | Non
 
 
 @router.get("/skills/{skill_id}/export")
-async def export_skill_v2(skill_id: int, request: Request,
+def export_skill_v2(skill_id: int, request: Request,
                           authorization: str | None = Header(default=None)):
     """Portable JSON document — POST it to /api/v2/skills/import elsewhere."""
     _guard(request, authorization)
@@ -618,7 +618,7 @@ async def export_skill_v2(skill_id: int, request: Request,
 
 
 @router.delete("/skills/{skill_id}")
-async def delete_skill_v2(skill_id: int, request: Request,
+def delete_skill_v2(skill_id: int, request: Request,
                           authorization: str | None = Header(default=None)):
     user = _guard(request, authorization, write=True)
     with get_conn() as conn: