CUB-41: Add low stock indicators to filament UI

frontend/src/app/models/agent.model.ts

@@ -0,0 +1,24 @@
+/**
+ * Represents the status of a single agent/printer in the system.
+ */
+export type AgentStatus = 'active' | 'idle' | 'thinking' | 'error';
+
+export interface AgentSummary {
+  /** Total number of agents in the system */
+  total: number;
+  /** Number of currently active agents */
+  active: number;
+  /** Number of currently idle agents */
+  idle: number;
+  /** Number of currently thinking/processing agents */
+  thinking: number;
+  /** Number of agents in error state */
+  error: number;
+}
+
+export interface SystemHealth {
+  /** Whether the SignalR connection is live */
+  connected: boolean;
+  /** Overall system health: healthy, degraded, or down */
+  status: 'healthy' | 'degraded' | 'down';
+}