Add native Android Internet Computer client and authentication flow

[humandebri]

Summary

• Add a native Android client for Internet Computer communication, CBOR/Candid encoding, identity management, and Internet Identity authentication
• Implement Kinic VFS, Ask AI, source capture, sharing, deep links, and app settings integration
• Add Android app-link and authentication callback routes to the web app
• Add unit and instrumentation coverage for the new Android functionality
• Configure Gradle, CI, runtime settings, and Android security metadata

Testing

• Not run (not requested)