BridgeJS: add runtime coverage for public @JS struct

[kateinoigakukun]

Motivation:

• Ensure @js public structs round-trip correctly at runtime to avoid regressions when exposing public Swift structs.

Overview:

• Add PublicPoint round-trip runtime fixture and JS prelude assertion.
• Regenerate BridgeJS bindings so the new public struct is reflected in generated Swift/JS artifacts.