ci: sign with consistent release keystore

.github/workflows/build-apk.yml

@@ -1,4 +1,4 @@
-name: Build Debug APK
+name: Build Release APK
 
 on:
   workflow_dispatch:
@@ -18,12 +18,21 @@ jobs:
       - name: Setup Android SDK
         uses: android-actions/setup-android@v3
 
-      - name: Build debug APK
-        run: ./gradlew assembleDebug
+      - name: Decode keystore
+        run: |
+          echo "${{ secrets.RELEASE_KEYSTORE_B64 }}" | base64 -d > $RUNNER_TEMP/helios-release.jks
+
+      - name: Build release APK
+        env:
+          RELEASE_KEYSTORE_PATH: ${{ runner.temp }}/helios-release.jks
+          RELEASE_KEYSTORE_PASS: ${{ secrets.RELEASE_KEYSTORE_PASS }}
+          RELEASE_KEY_ALIAS: helios
+          RELEASE_KEY_PASS: ${{ secrets.RELEASE_KEYSTORE_PASS }}
+        run: ./gradlew assembleRelease
 
       - name: Upload APK
         uses: actions/upload-artifact@v4
         with:
           name: helios-alarm-clock-debug
-          path: app/build/outputs/apk/debug/*.apk
+          path: app/build/outputs/apk/release/*.apk
           retention-days: 7