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/agent.py

@@ -213,7 +213,7 @@ async def create_conversation(request: Request):
 
 
 @router.get("/conversations/{conversation_id}")
-async def get_conversation(request: Request, conversation_id: int):
+def get_conversation(request: Request, conversation_id: int):
     with get_conn() as conn:
         conv = conn.execute("SELECT * FROM agent_conversations WHERE id=?", (conversation_id,)).fetchone()
         if not conv:
@@ -226,7 +226,7 @@ async def get_conversation(request: Request, conversation_id: int):
 
 
 @router.delete("/conversations/{conversation_id}")
-async def delete_conversation(request: Request, conversation_id: int):
+def delete_conversation(request: Request, conversation_id: int):
     with get_conn() as conn:
         if not conn.execute("SELECT id FROM agent_conversations WHERE id=?", (conversation_id,)).fetchone():
             raise HTTPException(status_code=404, detail="Conversation introuvable")
@@ -450,7 +450,7 @@ async def agent_writing_properties(request: Request):
 
 
 @router.get("/conversations/{conversation_id}/actions")
-async def list_actions(request: Request, conversation_id: int):
+def list_actions(request: Request, conversation_id: int):
     with get_conn() as conn:
         rows = conn.execute(
             "SELECT * FROM agent_actions WHERE conversation_id=? ORDER BY created_at, id",
@@ -460,7 +460,7 @@ async def list_actions(request: Request, conversation_id: int):
 
 
 @router.post("/actions/{action_id}/undo")
-async def undo(request: Request, action_id: int):
+def undo(request: Request, action_id: int):
     try:
         undo_action(action_id)
     except ValueError as exc:
@@ -528,7 +528,7 @@ async def apply_skill(request: Request, skill_id: int):
 
 
 @router.get("/skills/gallery")
-async def skills_gallery(request: Request):
+def skills_gallery(request: Request):
     presets = skill_gallery.list_gallery()
     return {"gallery": presets, "total": len(presets),
             "install": "POST /api/agent/skills/gallery/{slug}/install"}
@@ -577,7 +577,7 @@ async def import_skill(request: Request):
 
 
 @router.get("/skills/{skill_id}/export")
-async def export_skill(request: Request, skill_id: int):
+def export_skill(request: Request, skill_id: int):
     """Document JSON portable — à rejouer sur /api/agent/skills/import."""
     with get_conn() as conn:
         row = conn.execute("SELECT * FROM agent_skills WHERE id=?", (skill_id,)).fetchone()
@@ -587,7 +587,7 @@ async def export_skill(request: Request, skill_id: int):
 
 
 @router.delete("/skills/{skill_id}")
-async def delete_skill(request: Request, skill_id: int):
+def delete_skill(request: Request, skill_id: int):
     with get_conn() as conn:
         row = conn.execute("SELECT name FROM agent_skills WHERE id=?", (skill_id,)).fetchone()
         if not row:
@@ -794,7 +794,7 @@ async def trigger_agent(request: Request, agent_id: int):
 
 
 @router.get("/tools")
-async def list_tools(request: Request):
+def list_tools(request: Request):
     registry = ToolRegistry()
     tools = registry.schema()
     return {"tools": tools}
@@ -1081,7 +1081,7 @@ async def test_provider_config(request: Request):
 
 
 @router.get("/{agent_id}")
-async def get_agent(request: Request, agent_id: int):
+def get_agent(request: Request, agent_id: int):
     with get_conn() as conn:
         row = conn.execute("SELECT * FROM agents WHERE id=?", (agent_id,)).fetchone()
     if not row:
@@ -1116,7 +1116,7 @@ async def update_agent(request: Request, agent_id: int):
 
 
 @router.delete("/{agent_id}")
-async def delete_agent(request: Request, agent_id: int):
+def delete_agent(request: Request, agent_id: int):
     with get_conn() as conn:
         existing = conn.execute("SELECT * FROM agents WHERE id=?", (agent_id,)).fetchone()
         if not existing: