chore(ci): enable yarn cache in lint workflow

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

Author: brendan-kellam

.github/workflows/lint.yml

@@ -19,6 +19,8 @@ jobs:
         uses: actions/setup-node@v4
         with:
           node-version: '20.x'
+          cache: 'yarn'
+          cache-dependency-path: '**/yarn.lock'
 
       - name: Install
         run: yarn install --frozen-lockfile