fix(screener): silence ESLint no-empty / no-undef in canvas helpers

빈 catch 블록 3곳에 의도 주석 추가, test-setup.js 의 beforeEach
명시적 import. 우리 신규 코드의 lint error 0으로 정리.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/pages/stock/screener/hooks/useCanvasLayout.js

@@ -31,14 +31,14 @@ export function useCanvasLayout(initialPositions) {
   const updateNodePosition = useCallback((nodeId, pos) => {
     setPositions((prev) => {
       const next = { ...prev, [nodeId]: { x: pos.x, y: pos.y } };
-      try { localStorage.setItem(STORAGE_KEY, JSON.stringify(next)); } catch {}
+      try { localStorage.setItem(STORAGE_KEY, JSON.stringify(next)); } catch { /* ignore quota/security errors */ }
       return next;
     });
   }, []);
 
   const reset = useCallback(() => {
     setPositions(initialPositions);
-    try { localStorage.removeItem(STORAGE_KEY); } catch {}
+    try { localStorage.removeItem(STORAGE_KEY); } catch { /* ignore security errors */ }
   }, [initialPositions]);
 
   return { positions, updateNodePosition, reset };

src/pages/stock/screener/hooks/useScreenerMode.js

@@ -18,7 +18,7 @@ export function useScreenerMode() {
   const setMode = (m) => {
     if (!VALID_MODES.has(m)) return;
     setModeState(m);
-    try { localStorage.setItem(STORAGE_KEY, m); } catch {}
+    try { localStorage.setItem(STORAGE_KEY, m); } catch { /* ignore quota/security errors */ }
   };
 
   return { mode, setMode };

src/test-setup.js

@@ -1,3 +1,4 @@
+import { beforeEach } from 'vitest';
 import '@testing-library/jest-dom/vitest';
 
 // jsdom polyfills for react-flow