- Default model_unload_timeout from Never to Min5
- Fix Drop impl: use take() on watcher handle so clones from
initiate_model_load() don't kill the watcher thread
- Reset last_activity on model load to prevent immediate unload
- Upgrade watcher logging from debug to info level
- Remove duplicate "unloaded" event (unload_model already emits it)
Co-authored-by: CJ Pais <cj@cjpais.com>