feat: add processor tracing toggle to exchange detail views

Wire getActions on ProcessorTimeline and RouteFlow to send
SET_TRACED_PROCESSORS commands to all agents of the same application.
Tracing state managed via Zustand store with optimistic UI and rollback.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/stores/tracing-store.ts

@@ -0,0 +1,24 @@
+import { create } from 'zustand'
+
+interface TracingState {
+  tracedProcessors: Record<string, Set<string>>
+  isTraced: (appRoute: string, processorId: string) => boolean
+  toggleProcessor: (appRoute: string, processorId: string) => Set<string>
+}
+
+export const useTracingStore = create<TracingState>((set, get) => ({
+  tracedProcessors: {},
+
+  isTraced: (appRoute, processorId) =>
+    get().tracedProcessors[appRoute]?.has(processorId) ?? false,
+
+  toggleProcessor: (appRoute, processorId) => {
+    const current = new Set(get().tracedProcessors[appRoute] ?? [])
+    if (current.has(processorId)) current.delete(processorId)
+    else current.add(processorId)
+    set((state) => ({
+      tracedProcessors: { ...state.tracedProcessors, [appRoute]: current },
+    }))
+    return current
+  },
+}))