fix: A21 phase 2c — 190 routes hors loop, 86 % total (v7.26.0)

4 passes (283 → 93 routes async sur 667 = 86 % hors loop, avant 61 %) :

A. RACINE AUTH — `get_current_user` (auth/session.py) était `async def`
   SANS aucun await (cookie decode = synchrone) ; idem ses clones :
   `agent._current_user_id/_workspace_id/_current_admin` (34 sites) et
   `sso._require_admin` (corps 0 await, 6 sites) → `def` +
   47 `await` supprimés. Piège : 3 call sites passaient par l'alias `gcu`
   (grep littéral aveugle) — 8 tests en échec → corrigés.

B. Re-scan : 19 routes devenues SANS await → `def` (agent 8, sso 5,
   web_clipper 3, projects 2, auth 1…).

C/D. 155 routes dont les seuls awaits = `request.json()` / événements :
   - try/except `body = {}` → `Body(default={})` (même tolérance)
   - try/except `raise HTTPException(400)` → `Body(...)` REQUIS
     (422 FastAPI — aucun test ne couvrait le 400)
   - forme conditionnelle `request.json() if content-type else {}`
     (54 sites) → défaut `{}` (sans corps = `{}` dans les 2 cas)
   - `await fire_*` → `run_event_sync(...)` ; imports `Body` /
     `run_event_sync` ajoutés aux routers convertis

Reste async (93, justifié) : form/upload/file (22), réseau gitea/llm/oidc,
`_json_body` (9), 2 JSON inline en argument, 1 fallback logique
(capture_frontend_error), 1 lecture conditionnelle (web_clipper), mixtes.

suite **1089/1089** · ruff OK · docs à jour

app/routers/webauthn.py

@@ -10,7 +10,7 @@ from __future__ import annotations
 import secrets
 import time
 
-from fastapi import APIRouter, HTTPException, Request
+from fastapi import APIRouter, Body, HTTPException, Request
 from fastapi.responses import JSONResponse
 
 from app.auth.session import SessionManager
@@ -76,15 +76,11 @@ def register_begin(request: Request):
 
 
 @router.post("/register/finish")
-async def register_finish(request: Request):
+def register_finish(request: Request, body: dict = Body(default={})):
     if not _require_lib():
         raise HTTPException(501, "WebAuthn library not installed")
     from webauthn import verify_registration_response
     user = _session_user(request)
-    try:
-        body = await request.json()
-    except Exception:
-        body = {}
     challenge = _take_challenge(f"reg:{user['id']}")
     if not challenge:
         raise HTTPException(400, "Challenge expired — begin again")
@@ -115,14 +111,10 @@ async def register_finish(request: Request):
 
 
 @router.post("/login/begin")
-async def login_begin(request: Request):
+def login_begin(request: Request, body: dict = Body(default={})):
     if not _require_lib():
         raise HTTPException(501, "WebAuthn library not installed")
     from webauthn import generate_authentication_options, options_to_json
-    try:
-        body = await request.json()
-    except Exception:
-        body = {}
     login = (body.get("login") or "").strip()
     if not login:
         raise HTTPException(400, "login required")
@@ -144,14 +136,10 @@ async def login_begin(request: Request):
 
 
 @router.post("/login/finish")
-async def login_finish(request: Request):
+def login_finish(request: Request, body: dict = Body(default={})):
     if not _require_lib():
         raise HTTPException(501, "WebAuthn library not installed")
     from webauthn import verify_authentication_response
-    try:
-        body = await request.json()
-    except Exception:
-        body = {}
     login = (body.get("login") or "").strip()
     challenge = _take_challenge(f"login:{login}")
     if not login or not challenge: