release-blocker: release builds are signed with the debug key

[0takuc0mrade]

Problem

`android/app/build.gradle`:

```groovy
buildTypes { release { signingConfig signingConfigs.debug } }
```

Release-mode APKs/AABs are signed with the debug keystore, so they cannot be uploaded to the Play Store and are insecure. Direct release-readiness blocker.

Scope (low-code)

Add a `signingConfigs.release` block reading from an untracked `key.properties`, and point release at it. Small gradle edit plus a documented `key.properties` template.

Acceptance criteria

• Release `signingConfig` no longer references `signingConfigs.debug`.
• Keystore credentials read from an untracked `key.properties` (added to `.gitignore`), with a documented example.
• `flutter build appbundle --release` produces a non-debug-signed artifact.

[Jumongweb]

Hi maintainer, i will like to solve this issue

[Okorie2000-code]

Hi maintainer, would love to work on this issue, i have already reviewed the description and will submit a clean PR. kindly assign.

[Fabluchy]

Hi maintainer, I would love to work one this issue, I already reviewed the description and will submit a clean PR, please kindly assign.

[Clement-coder]

Hi,

I’m a full-stack software and blockchain engineer with hands-on experience delivering production-ready solutions across frontend, backend, and blockchain systems.

I’d like to take ownership of this issue. I’ve reviewed the requirements and can implement a scalable, maintainable, and well-tested solution that fully satisfies the acceptance criteria.

Ready to start immediately and keep the team updated throughout the process.

[BigManly4]

Hello maintainer, I would love to resolve this issue within few hours. I am a Full-Stack Dev with contributions to Oss projects. Please assign.

[BigNathan1]

Hello maintainer, I would love to resolve this issue within few hours. I am a Full-Stack Dev with contributions to Oss projects. Please assign.

[grantfox-oss]

🦊 GrantFox — @barry01-hash has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #130)
2. Your PR will be reviewed by the Nodus-protocol maintainers

Good luck! Track your progress on GrantFox.