ci: mark missing signing secrets as non-blocking error

.gitea/workflows/android-build.yml

@@ -55,6 +55,7 @@ jobs:
 
       - name: Prepare optional release signing
         if: github.event_name == 'release'
+        continue-on-error: true
         env:
           ANDROID_KEYSTORE_BASE64: ${{ secrets.ANDROID_KEYSTORE_BASE64 }}
           ANDROID_KEYSTORE_PASSWORD: ${{ secrets.ANDROID_KEYSTORE_PASSWORD }}
@@ -73,8 +74,8 @@ jobs:
           if [ ${#missing[@]} -gt 0 ]; then
             printf -v missing_csv '%s, ' "${missing[@]}"
             missing_csv="${missing_csv%, }"
-            echo "::warning::Release signing secrets missing: ${missing_csv}. Building unsigned/default-signed release AAB."
-            exit 0
+            echo "::error::Release signing secrets missing: ${missing_csv}. Continuing with unsigned/default-signed release AAB."
+            exit 1
           fi
 
           mkdir -p .ci-secrets