Enrich the patrol seed context with service identity (from discovery
store) and network reachability (via ICMP ping through host agents).
The guest metrics table now includes Service and Reachable columns,
and a Service Health Issues section highlights running-but-unreachable
guests. A new SignalGuestUnreachable signal type creates deterministic
findings for unreachable guests.
New files:
- patrol_intelligence.go: GuestProber interface, GuestIntelligence
type, gatherGuestIntelligence() with concurrent per-node probing
- patrol_prober.go: agentExecProber implementation using batch ping
commands via connected host agents
