fix: eliminate training panel flash on page load

- Don't restore applied state from localStorage on mount (was causing
  first-frame flash when skill was already enabled)
- Always start with applied=false; only set true on user click

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/app/app/assistant.tsx

@@ -338,11 +338,10 @@ function AssistantWorkspace() {
 	useEffect(() => {
 		if (skill.loading) return;
 		if (!skillLoadedOnce.current) {
-			// 初始加载完成，记录当前状态，不触发 applied
 			skillLoadedOnce.current = true;
 			prevSkillEnabled.current = skill.enabled;
-			// 关掉时清理 localStorage 残留
+			// 初始加载：无条件清除 applied（清 localStorage 残留），面板只从用户点击打开
-			if (!skill.enabled && applied) {
+			if (applied) {
 				setApplied(false);
 			}
 			return;

frontend/app/lib/use-training-mode.ts

@@ -71,18 +71,10 @@ export function useModelIterationEnabled(): {
 // - 刷新页面也保持
 // 不走后端 PATCH 是为了避开 __LOCALID_* 临时 session id 导致 404
 export function useAppliedTraining(sessionId: string | null) {
+	// 不再从 localStorage 恢复 applied 状态——面板只通过用户本次会话中
+	// 显式点击 skill 按钮打开，避免页面加载时闪烁。
 	const [applied, setApplied] = useState(false);
 
-	useEffect(() => {
-		if (!sessionId || typeof window === "undefined") {
-			setApplied(false);
-			return;
-		}
-		const stored =
-			window.localStorage.getItem(APPLIED_STORAGE_PREFIX + sessionId) === "1";
-		setApplied(stored);
-	}, [sessionId]);
-
 	const setAppliedPersist = useCallback(
 		(next: boolean) => {
 			setApplied(next);