ci: cache Electron binary and retry pnpm install on failure

Author: SDSLeon

.github/workflows/ci.yml

@@ -93,8 +93,25 @@ jobs:
           node-version: "24"
           cache: pnpm
 
+      - name: Cache Electron binary
+        uses: actions/cache@v5
+        with:
+          path: ~/.cache/electron
+          key: electron-${{ runner.os }}-${{ hashFiles('pnpm-lock.yaml') }}
+          restore-keys: |
+            electron-${{ runner.os }}-
+
       - name: Install dependencies
-        run: pnpm install --frozen-lockfile
+        run: |
+          for attempt in 1 2 3; do
+            if pnpm install --frozen-lockfile; then
+              exit 0
+            fi
+            echo "::warning::pnpm install failed on attempt $attempt; retrying in 15s"
+            sleep 15
+          done
+          echo "::error::pnpm install failed after 3 attempts"
+          exit 1
 
       - name: Test
         run: pnpm run test