Add status command (roadmap v0.8: status --json)

Add `enodia-sentinel status [--json]` — a local health and alert
summary: daemon running state, heartbeat freshness, per-severity alert
counts, last alert time, and eBPF state. Reuses web.daemon_status (the
same data behind /api/status), so the CLI and dashboard never diverge.

Exit code reflects health (0 = running and fresh, 1 = down or stale), so
it doubles as a cron/monitoring probe. Three CLI tests drive it against a
temp log_dir; no daemon or root needed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/COMMAND_REFERENCE.md

@@ -182,6 +182,23 @@ Exit code:
 
 ## Evidence and Operator Commands
 
+### `status`
+
+```bash
+enodia-sentinel status
+enodia-sentinel status --json
+```
+
+Prints a local health and alert summary: daemon running state, heartbeat age and
+staleness, total alerts with per-severity counts, last alert time, and eBPF
+monitor state. `--json` emits the same data as the dashboard `/api/status`
+endpoint, for cron/monitoring.
+
+Exit code:
+
+- `0`: daemon is running and the heartbeat is fresh.
+- `1`: daemon is down or the heartbeat is stale.
+
 ### `web`
 
 ```bash
@@ -238,7 +255,6 @@ does not require pip or a virtualenv.
 The roadmap reserves these command shapes:
 
 ```bash
-enodia-sentinel status --json
 enodia-sentinel incident list
 enodia-sentinel incident show <incident-id>
 enodia-sentinel incident export <incident-id>