Fix Gradle build cache save races with restore-only on parallel jobs.

Co-authored-by: Cursor <cursoragent@cursor.com>

.github/actions/cache-gradle-build/action.yml

@@ -1,6 +1,12 @@
 name: Cache Gradle build directories
 description: Restore or save module build/ trees for faster CI Gradle jobs
 
+inputs:
+  save:
+    description: Save cache at job end. Use false on parallel jobs that share the same cache key.
+    required: false
+    default: "true"
+
 outputs:
   cache-hit:
     description: Whether build directories were restored from cache
@@ -12,6 +18,7 @@ runs:
     - uses: actions/cache@v5
       id: cache
       with:
+        lookup-only: ${{ inputs.save != 'true' }}
         path: |
           app/desktop/build
           app/shared/build

.github/workflows/release.yml

@@ -86,6 +86,8 @@ jobs:
           version: ${{ needs.resolve-version.outputs.version }}
       - uses: ./.github/actions/cache-gradle-build
         id: gradle-build-cache
+        with:
+          save: "true"
       - name: Compile and ProGuard release desktop jars
         if: steps.gradle-build-cache.outputs.cache-hit != 'true'
         run: ./gradlew :app:desktop:exportReleaseProguardForCi --no-daemon --console=plain
@@ -108,6 +110,8 @@ jobs:
         with:
           version: ${{ needs.resolve-version.outputs.version }}
       - uses: ./.github/actions/cache-gradle-build
+        with:
+          save: "true"
       - uses: dtolnay/rust-toolchain@stable
         with:
           targets: x86_64-pc-windows-msvc
@@ -165,6 +169,8 @@ jobs:
         with:
           version: ${{ needs.resolve-version.outputs.version }}
       - uses: ./.github/actions/cache-gradle-build
+        with:
+          save: "false"
       - uses: actions/download-artifact@v5
         with:
           name: desktop-proguard
@@ -221,6 +227,8 @@ jobs:
         with:
           version: ${{ needs.resolve-version.outputs.version }}
       - uses: ./.github/actions/cache-gradle-build
+        with:
+          save: ${{ matrix.arch == 'arm64' }}
       - uses: actions/download-artifact@v5
         with:
           name: desktop-proguard
@@ -277,6 +285,8 @@ jobs:
         with:
           version: ${{ needs.resolve-version.outputs.version }}
       - uses: ./.github/actions/cache-gradle-build
+        with:
+          save: ${{ matrix.arch == 'arm64' }}
       - uses: actions/download-artifact@v5
         with:
           name: desktop-proguard
@@ -320,6 +330,8 @@ jobs:
         with:
           version: ${{ needs.resolve-version.outputs.version }}
       - uses: ./.github/actions/cache-gradle-build
+        with:
+          save: "false"
       - name: Cache Android SDK extras
         uses: actions/cache@v5
         with: