ENG-219: Add npm caching to CI workflows

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

Author: d4mation

.github/workflows/lint.yml

@@ -8,6 +8,7 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           node-version: 20
+          cache: 'npm'
       - run: npm ci
       - run: npm run lint
       - name: Typecheck

.github/workflows/tests.yml

@@ -11,6 +11,7 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           node-version: ${{ matrix.node-version }}
+          cache: 'npm'
       - run: npm ci
       - run: npm run build
       - name: Setup git