ci: add ESLint cache to speed up lint workflow

- Cache .eslintcache file between runs
- Use restore-keys for cross-branch cache fallback
- Only re-lint files that have changed

Author: pawelangelow

.github/workflows/lint.yml

@@ -13,6 +13,14 @@ jobs:
       - name: Install dependencies
         uses: ./.github/actions/install-all-build-libs
 
+      - name: Cache ESLint results
+        uses: actions/cache@v4
+        with:
+          path: .eslintcache
+          key: eslint-${{ runner.os }}-${{ hashFiles('**/*.js', '**/*.jsx', '**/*.ts', '**/*.tsx', '.eslintrc*', 'eslint.config.*') }}
+          restore-keys: |
+            eslint-${{ runner.os }}-
+
       - name: Run ESLint
-        run: yarn lint
+        run: yarn lint --cache --cache-location .eslintcache