feat: add macOS desktop client build workflow with ARM64 support and fix tunnel metrics task ownership

Add macos-desktop-client.yml workflow with manual dispatch trigger running on macos-arm64 runner. Install Node.js 22 and Rust toolchain with aarch64-apple-darwin target. Build bundled tunnel helper and Tauri application bundle, then upload .app, .dmg, and raw build artifacts.

Fix tunnel_metrics handler to clone app handle before spawn_blocking to prevent ownership issues when passing to tunnel

.gitea/workflows/macos-desktop-client.yml

@@ -0,0 +1,55 @@
+name: Build macOS Desktop Client
+
+on:
+  workflow_dispatch:
+
+jobs:
+  build-macos-client:
+    name: Build macOS Client
+    runs-on: macos-arm64
+
+    defaults:
+      run:
+        shell: bash
+        working-directory: desktop-client
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: "22"
+
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: aarch64-apple-darwin
+
+      - name: Install desktop client dependencies
+        run: npm install
+
+      - name: Build bundled macOS tunnel helper
+        run: npm run helper:macos-arm64
+
+      - name: Build macOS application bundle
+        run: npx tauri build --target aarch64-apple-darwin
+
+      - name: Upload macOS app bundle
+        uses: christopherhx/gitea-upload-artifact@v4
+        with:
+          name: NexaVPN-macos-app
+          path: |
+            desktop-client/src-tauri/target/aarch64-apple-darwin/release/bundle/macos/*.app
+            desktop-client/src-tauri/target/aarch64-apple-darwin/release/bundle/dmg/*.dmg
+          if-no-files-found: error
+
+      - name: Upload raw macOS build outputs
+        uses: christopherhx/gitea-upload-artifact@v4
+        with:
+          name: NexaVPN-macos-raw-build
+          path: |
+            desktop-client/src-tauri/target/aarch64-apple-darwin/release/nexavpn-desktop
+            desktop-client/src-tauri/bundled/macos-arm64/nexavpn-tunnel-helper
+          if-no-files-found: error