ci: add Gitea Actions workflow to build and attach APK on tag push

Triggers on v* tags — sets up Java 17 + Android SDK, builds a debug APK
(installable without a keystore), renames it SyncFlow-v<version>.apk, and
uploads it to the matching Gitea release via the API using the built-in token.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/release.yml

@@ -0,0 +1,52 @@
+name: Build & Release APK
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-java@v4
+        with:
+          java-version: '17'
+          distribution: 'temurin'
+          cache: gradle
+
+      - uses: android-actions/setup-android@v3
+
+      - name: Build debug APK
+        run: |
+          chmod +x gradlew
+          ./gradlew assembleDebug --no-daemon
+
+      - name: Get version name
+        id: ver
+        run: echo "name=$(grep VERSION_NAME version.properties | cut -d= -f2)" >> $GITHUB_OUTPUT
+
+      - name: Rename APK
+        run: |
+          mkdir dist
+          cp app/build/outputs/apk/debug/app-debug.apk \
+             dist/SyncFlow-v${{ steps.ver.outputs.name }}.apk
+
+      - name: Attach APK to release
+        env:
+          TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          TAG: ${{ github.ref_name }}
+          VERSION: ${{ steps.ver.outputs.name }}
+        run: |
+          RELEASE_ID=$(curl -sf \
+            "https://gitea.khodak.me/api/v1/repos/amir/SyncFlow/releases/tags/$TAG" \
+            -H "Authorization: token $TOKEN" \
+            | python3 -c "import sys,json; print(json.load(sys.stdin)['id'])")
+          curl -sf -X POST \
+            "https://gitea.khodak.me/api/v1/repos/amir/SyncFlow/releases/$RELEASE_ID/assets" \
+            -H "Authorization: token $TOKEN" \
+            -F "attachment=@dist/SyncFlow-v${VERSION}.apk"
+          echo "APK uploaded to release $TAG"