ci: add macOS (DMG) and Windows (ZIP) build jobs

- mac-runner: builds macOS .dmg with flutter build macos
- windows-runner: builds Windows .zip with flutter build windows
- Both depend on test passing before building

.github/workflows/ci.yml

@@ -68,3 +68,52 @@ jobs:
         with:
           name: habo-linux
           path: build/linux/x64/release/bundle/
+
+  build-macos:
+    needs: test
+    runs-on: mac-runner
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup Flutter
+        uses: subosito/flutter-action@v2
+        with:
+          flutter-version: '3.35.7'
+      - name: Install macOS deps
+        run: |
+          brew install cocoapods
+      - name: Get dependencies
+        run: flutter pub get
+      - name: Build macOS
+        run: flutter build macos --release
+      - name: Create DMG
+        run: |
+          cd build/macos/Build/Products/Release
+          hdiutil create -volname Habo -srcfolder habo.app -ov -format UDZO habo.dmg
+      - name: Upload artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: habo-macos
+          path: build/macos/Build/Products/Release/habo.dmg
+
+  build-windows:
+    needs: test
+    runs-on: windows-runner
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup Flutter
+        uses: subosito/flutter-action@v2
+        with:
+          flutter-version: '3.35.7'
+      - name: Get dependencies
+        run: flutter pub get
+      - name: Build Windows
+        run: flutter build windows --release
+      - name: Create ZIP
+        run: |
+          cd build/windows/x64/runner/Release
+          Compress-Archive -Path * -DestinationPath habo-windows.zip
+      - name: Upload artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: habo-windows
+          path: build/windows/x64/runner/Release/habo-windows.zip