Add WASM Component Model (WIT) interop support.

Motivation

The WASM Component Model enables Vera components to interoperate with components written in Rust, Go, Python, and other languages via WIT (WebAssembly Interface Type) interfaces. This is critical for ecosystem access — Vera does not need to implement every library natively if it can call into existing components.

Proposed work

• Generate WIT interface definitions from Vera module signatures
• Consume WIT interfaces as Vera module imports
• Compile Vera modules as WASM components (not just core WASM modules)

Context

The Component Model is Phase 2/3 in W3C standardization and production-ready in Wasmtime and Fermyon Spin. It provides a standard ABI for cross-language function calls, typed data exchange, and resource management.

Dependencies

• WASI 0.2 compliance (new issue) — components build on WASI