feat: add frontend lint checks to CI

- Add ESLint config (eslint.config.js) for ESLint 9
- Add ESLint dependencies to package.json
- Update CI workflow to include:
  - ESLint check
  - Prettier format check
- Fix lint errors:
  - Remove unused catch variable in Logs.tsx
  - Add eslint-disable for intentional useEffect dependency
- Run prettier to format all source files

.github/workflows/ci.yml

@@ -62,6 +62,12 @@ jobs:
       - name: TypeScript check
         run: npx tsc --noEmit
 
+      - name: ESLint check
+        run: npm run lint
+
+      - name: Prettier check
+        run: npx prettier --check "src/**/*.{ts,tsx,css}"
+
   build-check:
     name: Build Check
     runs-on: ubuntu-latest