fix: add build step to lint job in CI workflow

The lint job needs packages to be built first because @tpmjs/ui's
lint script runs eslint, which is a local dependency that needs
the package to be built before it can be executed.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

.github/workflows/ci.yml

@@ -28,6 +28,9 @@ jobs:
       - name: Install dependencies
         run: pnpm install --frozen-lockfile
 
+      - name: Build packages
+        run: pnpm build
+
       - name: Lint
         run: pnpm lint