Moves concurrency, queue drain, workspace lifecycle, and frozen state
from agentic/prep into pkg/runner/ — a standalone Core service that
communicates via IPC Actions only.
- runner.Register wires Actions: dispatch, status, start, stop, kill, poke
- runner.HandleIPCEvents catches AgentCompleted → ChannelPush + queue poke
- Agentic dispatch asks runner for permission via c.Action("runner.dispatch")
- Dispatch mutex moved to struct-level sync.Mutex (fixes core.Lock init race)
- Registry-based concurrency counting replaces disk scanning
- TrackWorkspace called on both queued and running status writes
- SpawnQueued message added for runner→agentic spawn requests
- ChannelPush message in core/mcp enables any service to push channel events
- 51 new tests covering runner service, queue, and config parsing
Co-Authored-By: Virgil <virgil@lethean.io>
