feat(ws): add task.deliver receive, task.started emission, and queue integration

[iAziz786]

Summary

Extend the Hostlink WebSocket client from handshake-only traffic to full task delivery receipt, started acknowledgements, and local queue integration.

Changes

• wsprotocol.TaskDeliverPayload added with command/priority fields and validation.
• localtaskstore.ReceiptStore interface extended with RecordStarted.
• wsclient.Client gains TaskEnqueuer and ReceiptStore:
  • receiveTaskDeliver: decodes payload, consults durable state, records receipt, sends task.received, enqueues only for new attempts. Running duplicates reply with task.started; final duplicates resend unacked terminal.
  • SendStarted: persists running state, sends task.started envelope.
• taskjob.ResultChannel extended with SendStarted. Called after execCmd.Start() — kill-and-fallback to HTTP if start fails.
• TaskJob.Enqueue adds in-memory buffered channel worker, wired as WS TaskEnqueuer in main.go.

Test cases added

• New delivery: recorded, received sent, queued once.
• Running duplicate: started sent, not requeued.
• Received duplicate: re-acked, not requeued.
• Final duplicate: unacked terminal replayed, not requeued.
• SendStarted: state persisted as running, envelope sent.
• TaskJob: verifies started emission on successful start.