- gate startServer on KIMI_CODE_EXPERIMENTAL_MULTI_SERVER: register under server/instances/ and rely on port+1 retry for coexistence, or take the legacy single-instance lock when off
- release/update the chosen handle on close, boot refusal, and after bind so the advertised port stays accurate
- export the instance registry API from the package barrel
- fix session.meta.updated to dispatch under the real session id instead of '__global__' so auto-titled and renamed sessions update in clients