Add Android build workflow and setup for APK generation

.gitea/workflows/Create Release.yml

@@ -64,6 +64,20 @@ jobs:
           cache: 'npm'
           cache-dependency-path: web/package-lock.json
 
+      - name: Setup Java
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: '17'
+
+      - name: Setup Android SDK
+        uses: android-actions/setup-android@v3
+
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@v4
+        with:
+          gradle-version: '8.7'
+
       - name: Build frontend
         run: |
           cd web
@@ -75,6 +89,17 @@ jobs:
           echo "Frontend build completed"
           ls -la internal/server/app/dist/
 
+      - name: Build Android release APK
+        run: |
+          cd android
+          gradle --no-daemon assembleRelease
+          cd ..
+          mkdir -p dist
+          cp android/app/build/outputs/apk/release/app-release-unsigned.apk \
+            "dist/gotunnel-android-${{ inputs.version }}-release-unsigned.apk"
+          echo "Android APK build completed"
+          ls -lah dist/gotunnel-android-${{ inputs.version }}-release-unsigned.apk
+
       - name: Build all platforms
         run: |
           mkdir -p dist
@@ -182,6 +207,7 @@ jobs:
             echo "- **Linux (amd64/arm64)**: \`.tar.gz\` files" >> release_notes.md
             echo "- **macOS (amd64/arm64)**: \`.tar.gz\` files" >> release_notes.md
             echo "- **Windows (amd64)**: \`.zip\` files" >> release_notes.md
+            echo "- **Android**: unsigned \`.apk\` file" >> release_notes.md
             echo "" >> release_notes.md
             echo "Verify downloads with \`SHA256SUMS\`" >> release_notes.md
           fi
@@ -197,6 +223,7 @@ jobs:
           files: |-
             dist/*.tar.gz
             dist/*.zip
+            dist/*.apk
             dist/SHA256SUMS
           draft: ${{ inputs.draft }}
           prerelease: ${{ inputs.prerelease }}

.gitea/workflows/build.yaml

@@ -40,6 +40,37 @@ jobs:
           path: web/dist
           retention-days: 1
 
+  build-android-apk:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Java
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: '17'
+
+      - name: Setup Android SDK
+        uses: android-actions/setup-android@v3
+
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@v4
+        with:
+          gradle-version: '8.7'
+
+      - name: Build Android debug APK
+        working-directory: android
+        run: gradle --no-daemon assembleDebug
+
+      - name: Upload Android APK
+        uses: actions/upload-artifact@v3
+        with:
+          name: gotunnel-android-debug-apk
+          path: android/app/build/outputs/apk/debug/app-debug.apk
+          retention-days: 7
+
   build-binaries:
     needs: build-frontend
     runs-on: golang