* git commit -m "feat: add SchedulerStarted and SchedulerStopped monitoring"
* fix lint issue
* Update errors.go
Co-authored-by: John Roesler <johnrroesler@gmail.com>
* feat() updated with remaning metrics & events (JobRegistered/JobUnregistered, JobStarted/JobRunning/JobFailed/JobCompleted)
* feat: enhance scheduler and job observability by adding new monitor events for lifecycle, performance, and concurrency limits.
* docs: expand metrics section to include scheduler lifecycle events and `SchedulerMonitor` details with Prometheus example
* refactor: conditionally send scheduler notifications only when a scheduler monitor is configured.
---------
Co-authored-by: John Roesler <johnrroesler@gmail.com>