## What changed
- Include `environmentInfo` in the exec-server `initialize` response and seed the Rust client's metadata cache from it.
- Fall back to one lazy `environment/info` request when connecting to older servers that omit initialization metadata, then share the cached result across client clones and session recovery.
- Keep app-server `environment/info` requests uncached so they continue to probe the executor.
## Testing
- Cover initialization metadata, the legacy-server fallback, shared caching, accepted WebSocket environments, and repeated uncached app-server probes.
GitOrigin-RevId: 380132d9db183998d73e8c6b0954e4d70c7e8406