Fix TDZ crash: move useEffect hooks to after runLint declaration

useEffect(() => {...}, [runLint]) evaluated [runLint] immediately,
but runLint was declared with const on the next line — temporal dead
zone. Moved both effects to after the useCallback closes.

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

frontend/src/components/Editor.jsx

@@ -153,11 +153,6 @@ const Editor = forwardRef(function Editor(
   }, [editor, content])
 
   // ── Lint check ───────────────────────────────────────────────────────────
-  // Keep ref in sync so the onUpdate closure (which never re-captures) always
-  // calls the latest version of runLint.
-  useEffect(() => { runLintRef.current = runLint }, [runLint])
-  useEffect(() => () => clearTimeout(lintDebounce.current), [])
-
   const runLint = useCallback(async () => {
     if (!editor || lintStatusRef.current === 'checking') return
     lintStatusRef.current = 'checking'
@@ -208,6 +203,11 @@ const Editor = forwardRef(function Editor(
     }
   }, [editor])
 
+  // Keep ref in sync so the stale onUpdate closure always calls the latest runLint
+  useEffect(() => { runLintRef.current = runLint }, [runLint])
+  // Clean up the debounce timer on unmount
+  useEffect(() => () => clearTimeout(lintDebounce.current), [])
+
   // ── Popover on clicking a lint mark ──────────────────────────────────────
   function handleEditorClick(e) {
     if (!editor) return