0001-stateful-import-resolver

We introduced a stateful ImportResolver trait utilizing thread-safe interior mutability (RwLock and OnceLock) for caching module boundaries and file existence checks, replacing the previous stateless function pointer resolution.

This design satisfies Rust’s thread-safety constraints (Send + Sync) to allow gradual migration of 8 languages, prepares the pipeline for parallelized import resolution under Rayon, and supports persistent cache reuse across incremental compilation runs.