fix: set account_id on all Session constructors; fix 3 ESLint errors in CI

Backend: start_session, prepare_session, batch_launch_sessions all missing
account_id=current_user.account_id — Phase 1 NOT NULL constraint made these
500 in test suite (test_ratings.py fixture couldn't create sessions).

Frontend ESLint:
- TaskLane.tsx: suppress react-refresh/only-export-components for clearTaskState
- TeamSummary.tsx: init loading from isAccountOwner to avoid sync setState in effect
- ScriptBodyEditor.tsx: move lastValueRef.current assignment into useEffect

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/components/dashboard/TeamSummary.tsx

@@ -9,10 +9,10 @@ export function TeamSummary() {
   const { isAccountOwner } = usePermissions()
   const navigate = useNavigate()
   const [escalationCount, setEscalationCount] = useState(0)
-  const [loading, setLoading] = useState(true)
+  const [loading, setLoading] = useState(!!isAccountOwner)
 
   useEffect(() => {
-    if (!isAccountOwner) { setLoading(false); return }
+    if (!isAccountOwner) return
     aiSessionsApi.getEscalationQueue()
       .then((esc) => setEscalationCount(esc.length))
       .catch(() => {})