chore: clean up generated mobile artifacts

[pwltr]

Summary

• Add script, Cargo, Gradle, Python metadata, and SwiftPM manifest validation workflows
• Add iOS bindgen workflow that generates Swift/XCFramework outputs and uploads review artifacts
• Add Android bindgen workflow that generates Kotlin/JNI/debug-symbol/AAR outputs and uploads review artifacts
• Stop tracking generated Android Kotlin bindings and regenerated mobile build outputs
• Stop tracking the generated Python wrapper while keeping Python package metadata, tests, and generation scripts
• Write deterministic iOS XCFramework archives to dist/ios for stable SwiftPM checksums
• Use setup-android v4 with an explicit empty package list to avoid the obsolete default tools package

Notes

This keeps the small checked-in Swift package structure needed by the local bindings package, while generated binaries and Android/Python bindgen output are rebuilt by scripts/CI.

The workflow/path-filter shape follows the VSS cleanup template, adapted for ldk-node’s bindings/swift, bindings/kotlin, and existing Python package layout.