ci(android): build the signed release on tags and on request

The signing secrets are now configured, so the job no longer needs to be
switched off. It runs for v* tags and for a manual dispatch with
signed_release set.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.github/workflows/android.yml

@@ -126,7 +126,7 @@ jobs:
 
   signed-release:
     name: Signed release
-    if: false
+    if: startsWith(github.ref, 'refs/tags/v') || inputs.signed_release
     needs: build
     runs-on: ubuntu-24.04
     env: