ci: flatpak build

.github/workflows/build.yml

@@ -379,8 +379,56 @@ jobs:
           name: linux-app
           path: plezy-linux.tar.gz
 
+  build-flatpak:
+    runs-on: ubuntu-latest
+    permissions:
+      id-token: write
+      attestations: write
+      contents: read
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Replace version placeholders
+        run: |
+          # Extract version from pubspec.yaml (e.g., "1.3.1+10" -> "1.3.1")
+          VERSION=$(grep '^version:' pubspec.yaml | sed 's/version: //' | sed 's/+.*//' | tr -d ' ')
+          DATE=$(date -u +%Y-%m-%d)
+
+          echo "Version: $VERSION"
+          echo "Date: $DATE"
+
+          # Replace placeholders in metainfo.xml
+          sed -i "s/{{VERSION}}/$VERSION/g" linux/com.edde746.plezy.metainfo.xml
+          sed -i "s/{{DATE}}/$DATE/g" linux/com.edde746.plezy.metainfo.xml
+
+      - name: Preprocess Flatpak manifest with flatpak-flutter
+        run: |
+          docker run --rm \
+            -v "$PWD":/usr/src/flatpak \
+            -u $(id -u):$(id -g) \
+            theappgineer/flatpak-flutter:latest \
+            linux/com.edde746.plezy.yml
+
+      - name: Build Flatpak
+        uses: flatpak/flatpak-github-actions/flatpak-builder@v6
+        with:
+          bundle: plezy.flatpak
+          manifest-path: linux/com.edde746.plezy.yml
+          cache-key: flatpak-builder-${{ github.sha }}
+
+      - name: Attest Flatpak
+        uses: actions/attest-build-provenance@v2
+        with:
+          subject-path: plezy.flatpak
+
+      - name: Upload Flatpak
+        uses: actions/upload-artifact@v4
+        with:
+          name: linux-flatpak
+          path: plezy.flatpak
+
   create-release:
-    needs: [build-android, build-ios, build-macos, build-windows, build-linux]
+    needs: [build-android, build-ios, build-macos, build-windows, build-linux, build-flatpak]
     runs-on: ubuntu-latest
     permissions:
       contents: write
@@ -403,6 +451,7 @@ jobs:
             artifacts/windows-portable/plezy-windows-portable.zip
             artifacts/windows-installer/plezy-windows-installer.exe
             artifacts/linux-app/plezy-linux.tar.gz
+            artifacts/linux-flatpak/plezy.flatpak
           draft: true
           prerelease: false
           generate_release_notes: true