feat(codegen): generate wasm bridge callbacks

[pgherveou]

Summary

Adds the generated Rust wasm-bindgen platform bridge and derives host callback namespace/adapter names from truapi-platform trait metadata.

The codegen pipeline no longer hardcodes the current platform trait set. Adding a new platform trait should only require providing the corresponding JS namespace/adapter implementation, not changing the Rust/TS codegen selection logic.

This layer also updates generated goldens for namespaced HostCallbacks, FlatHostCallbacks compatibility, RequiredHostCallbacks, and encoded platform-local bridge payloads.

Stack

Part of the Rust core runtime port umbrella #104. Full port sequence:

1. feat(truapi): add testing API and versioned wiring #248 - layer 1/9, merged historical: truapi testing API and versioned wiring.
2. feat(truapi-platform): add host capability traits #249 - layer 2/9, merged historical: truapi-platform host capability traits.
3. feat(truapi-codegen): emit Rust dispatcher, wire table, and host callbacks #254 - layer 3/9, merged historical: codegen Rust dispatcher, wire table, and host callbacks.
4. feat(truapi-server): add host logic primitives #255 - layer 4/9, merged historical: server host logic primitives.
5. feat(truapi-server): add wire and chain infrastructure #256 - layer 5/9, merged historical: server wire and chain infrastructure.
6. feat(truapi-server): add platform runtime and host bridge #250 - active layer 1/4: server runtime, permissions, lifecycle, and permission-flow docs.
7. 👉 feat(codegen): generate wasm bridge callbacks #265 - active layer 2/4: generic wasm bridge/codegen layer. This PR.
8. feat(host-wasm): add @parity/truapi-host-wasm runtime #252 - active layer 3/4: @parity/truapi-host-wasm namespaced callback consumer.
9. chore: docs, CI, tooling, and dotli integration for the Rust core #253 - active layer 4/4, top: docs, CI/tooling, playground, and dotli integration.

Active child #253 is kept tree-equivalent with umbrella #104.

Validation

• cargo fmt --all --check
• cargo check -p truapi-codegen
• cargo check -p truapi-server
• cargo test -p truapi-codegen golden_
• TRUAPI_SKIP_PACKAGE_BUILD=1 ./scripts/codegen.sh