Add endpoint monitor catalog and warn-only drift reconciler

Operators need to see when a machine's running services or processes fall outside the desired state defined by policy. This adds a reusable monitor catalog (shipped read-only rows plus user-built local rows), computes drift server-side on agent check-in, and surfaces a warning on the endpoint panels. Remediation stays manual for now; automation can follow once demand is proven. Includes migrations 0006-0008 and the monitors API client.

plugins/endpoints/models/endpoint.py

@@ -75,6 +75,13 @@ class EndpointState(db.Model):
     interfacesjson = db.Column(db.Text(length=16777215), nullable=True)
     scheduledtasksjson = db.Column(db.Text(length=16777215), nullable=True)
 
+    # Warn-only reconciler output, refreshed on every agent check-in in the same
+    # commit as servicesjson. Each entry names a policy/shipped-attached monitor
+    # the endpoint is expected to be running but the latest snapshot does not
+    # report as running, so an operator sees the drift and intervenes manually.
+    # This is warn-only: nothing here is auto-remediated. Null = never computed.
+    driftjson = db.Column(db.Text(length=16777215), nullable=True)
+
     # Last-known MTConnect agent run state, cached so the WebUI toggle can show
     # a real state between command polls. Set by the agent's mtconnect_status
     # result. Null = never reported (unknown).