Add pnpm store caching to speed up builds

Co-Authored-By: Warp <agent@warp.dev>

Author: erinmikailstaples

.github/workflows/preview-deploy.yml

@@ -33,6 +33,18 @@ jobs:
         with:
           version: 9
 
+      - name: Get pnpm store directory
+        shell: bash
+        run: echo "STORE_PATH=$(pnpm store path --silent)" >> $GITHUB_ENV
+
+      - name: Cache pnpm store
+        uses: actions/cache@v4
+        with:
+          path: ${{ env.STORE_PATH }}
+          key: ${{ runner.os }}-pnpm-store-${{ hashFiles('**/pnpm-lock.yaml') }}
+          restore-keys: |
+            ${{ runner.os }}-pnpm-store-
+
       - name: Install dependencies
         run: pnpm install --frozen-lockfile