- api: add fillServiceStatus helper and call it from getServiceList/getService
so status field appears in service list and detail API responses
- observeStats: unify retry pattern across all 9 handlers (http, http2, masque,
relay, router, socks4, socks5, tungo, tunnel) — buffer events on failure,
continue to skip fresh collection, clear on success; fix event-loss bug
where interim events were dropped during retry cycles
- handler/router: check WriteTo/Write return errors in associate.go and
entrypoint.go; fix DelConnector and ConnectorPool.Del using RLock instead
of Lock (write under read lock); remove unused fields t and cancel