feat(wrpc): add transport abstraction and language-specific bindings (Phase 3+4)

[avrabe]

Summary

This PR implements Phase 3 (Transport Abstraction Layer) and Phase 4 (Multi-Language Support) of the WRPC modernization effort (#332).

Phase 3 - Transport Abstraction Layer

• Added WrpcTransportInfo provider for pluggable transport configuration
• Created transport configuration rules with address validation:
  • tcp_transport: Direct TCP connections (host:port)
  • nats_transport: NATS.io messaging (nats://host:port)
  • unix_transport: Unix domain sockets (/path/to/socket)
  • quic_transport: QUIC protocol (host:port)
• Updated wrpc_serve to accept transport attribute for type-safe configuration
• Backward compatible with legacy string-based transport/address attributes

Phase 4 - Multi-Language Binding Support

• Added wrpc_rust_bindings() macro for idiomatic Rust binding generation
• Added wrpc_go_bindings() macro for idiomatic Go binding generation
• Note: wit-bindgen-wrpc only supports Rust and Go (not Python/JavaScript)

Usage Examples

load("@rules_wasm_component//wrpc:transports.bzl", "tcp_transport")
load("@rules_wasm_component//wrpc:defs.bzl", "wrpc_serve", "wrpc_rust_bindings")

# Define transport configuration
tcp_transport(
    name = "dev_server",
    address = "localhost:8080",
)

# Serve a component
wrpc_serve(
    name = "serve",
    component = ":my_component",
    transport = ":dev_server",
)

# Generate Rust bindings
wrpc_rust_bindings(
    name = "calculator_client",
    wit = "//wit:calculator",
    world = "calculator-client",
)

Test plan

• Build verification: bazel build //wrpc:defs //wrpc:transports //providers:providers
• CI passes

Closes #332

🤖 Generated with Claude Code