Add src/app/operations.go with the seven intents that make the Service
the sole writer of job and runtime state: CreateJob, UpdateJob,
DeleteJob, SetEnabled, RunNow, SetGlobalPause, UpdateSettings. Each
returns error, persists through the store, and announces changes via
RunRecorded/JobChanged/SchedulerStateChanged events.
Extend the Service with a parsed-schedule cache, a global paused flag,
an injectable runJob seam (defaults to runner.RunJob) for testing the
run-now path, and a lifecycle ctx. Run and next-run timing now live in
the Service (duplicating the scheduler temporarily); T3.4 converts the
scheduler to drive the Service and removes the duplication.
Autostart is left to the caller until T5.2's injectable Manager; async
save errors in the run goroutine remain deferred to T5.1. Adds 12 tests
covering create/update/delete, enable/pause, global pause, run-now with
a fake runner, and settings persistence/validation.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
