fix(ci): prevent partial releases when a build job fails

Restructure the release workflow so build jobs upload workflow artifacts
instead of creating GitHub releases directly. A single finalize-release
job downloads all artifacts and creates the release only when every
platform build succeeds. Also removes the unused gradle bundle step
from the Android job and adds retry logic to gradlew assembleRelease.

scripts/release-body.js

@@ -21,7 +21,8 @@ try {
   files = readdirSync(distDir);
 } catch {}
 
-// In CI finalization, dist is empty. Prefer GitHub release assets when available.
+// In CI finalization, dist is populated from downloaded workflow artifacts.
+// Falls back to GitHub release assets for local/manual runs.
 const getReleaseAssetNames = async () => {
   try {
     const token = process.env.GITHUB_TOKEN;