feat: add release signing for lsposed and test-app APKs

- Add signingConfigs to both build.gradle.kts files, reading keystore
  credentials from keystore.properties (gitignored, local absolute path)
- Both debug and release builds use the same signing key for consistent
  signatures between local and CI builds
- CI decodes keystore from ANDROID_KEYSTORE_BASE64 secret, builds
  assembleRelease instead of assembleDebug
- Add keystore-related files to .gitignore for test-app

.github/workflows/ci.yml

@@ -143,10 +143,24 @@ jobs:
       - name: Set up Gradle
         uses: gradle/actions/setup-gradle@v4
 
+      - name: Set up keystore
+        env:
+          KEYSTORE_BASE64: ${{ secrets.ANDROID_KEYSTORE_BASE64 }}
+          KEYSTORE_PASSWORD: ${{ secrets.ANDROID_KEYSTORE_PASSWORD }}
+          KEY_ALIAS: ${{ secrets.ANDROID_KEY_ALIAS }}
+        run: |
+          KEYSTORE_PATH="${{ github.workspace }}/lsposed/release.jks"
+          echo "$KEYSTORE_BASE64" | base64 --decode > "$KEYSTORE_PATH"
+          cat > lsposed/keystore.properties <<EOF
+          password=$KEYSTORE_PASSWORD
+          keyAlias=$KEY_ALIAS
+          storeFile=$KEYSTORE_PATH
+          EOF
+
       - name: Build APK
         run: |
-          cd lsposed && ./gradlew --no-daemon assembleDebug
-          cp app/build/outputs/apk/debug/app-debug.apk "$GITHUB_WORKSPACE/vpnhide-lsposed.apk"
+          cd lsposed && ./gradlew --no-daemon assembleRelease
+          cp app/build/outputs/apk/release/app-release.apk "$GITHUB_WORKSPACE/vpnhide-lsposed.apk"
 
       - name: Upload artifact
         uses: actions/upload-artifact@v4
@@ -182,12 +196,26 @@ jobs:
         with:
           ndk-version: r28b
 
+      - name: Set up keystore
+        env:
+          KEYSTORE_BASE64: ${{ secrets.ANDROID_KEYSTORE_BASE64 }}
+          KEYSTORE_PASSWORD: ${{ secrets.ANDROID_KEYSTORE_PASSWORD }}
+          KEY_ALIAS: ${{ secrets.ANDROID_KEY_ALIAS }}
+        run: |
+          KEYSTORE_PATH="${{ github.workspace }}/test-app/release.jks"
+          echo "$KEYSTORE_BASE64" | base64 --decode > "$KEYSTORE_PATH"
+          cat > test-app/keystore.properties <<EOF
+          password=$KEYSTORE_PASSWORD
+          keyAlias=$KEY_ALIAS
+          storeFile=$KEYSTORE_PATH
+          EOF
+
       - name: Build APK
         run: |
           . "$HOME/.cargo/env"
           export ANDROID_NDK_HOME=${{ steps.ndk.outputs.ndk-path }}
-          cd test-app && ./gradlew --no-daemon assembleDebug
-          cp app/build/outputs/apk/debug/app-debug.apk "$GITHUB_WORKSPACE/vpnhide-test.apk"
+          cd test-app && ./gradlew --no-daemon assembleRelease
+          cp app/build/outputs/apk/release/app-release.apk "$GITHUB_WORKSPACE/vpnhide-test.apk"
 
       - name: Upload artifact
         uses: actions/upload-artifact@v4