feat: add application config overview and inline editing

Add admin page at /admin/appconfig with a DataTable showing all
application configurations. Inline dropdowns allow editing log level,
engine level, payload capture mode, and metrics toggle directly from
the table. Changes push to agents via SSE immediately.

Also adds a config bar on the AgentHealth page (/agents/:appId) for
per-application config management with the same 4 settings.

Backend: GET /api/v1/config list endpoint, findAll() on repository,
sensible defaults for logForwardingLevel/engineLevel/payloadCaptureMode.

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

ui/src/api/queries/commands.ts

@@ -10,6 +10,7 @@ export interface ApplicationConfig {
   updatedAt?: string
   engineLevel?: string
   payloadCaptureMode?: string
+  logForwardingLevel?: string
   metricsEnabled: boolean
   samplingRate: number
   tracedProcessors: Record<string, string>
@@ -24,6 +25,17 @@ function authFetch(url: string, init?: RequestInit): Promise<Response> {
   return fetch(url, { ...init, headers })
 }
 
+export function useAllApplicationConfigs() {
+  return useQuery({
+    queryKey: ['applicationConfig', 'all'],
+    queryFn: async () => {
+      const res = await authFetch('/api/v1/config')
+      if (!res.ok) throw new Error('Failed to fetch configs')
+      return res.json() as Promise<ApplicationConfig[]>
+    },
+  })
+}
+
 export function useApplicationConfig(application: string | undefined) {
   return useQuery({
     queryKey: ['applicationConfig', application],
@@ -50,6 +62,7 @@ export function useUpdateApplicationConfig() {
     },
     onSuccess: (saved) => {
       queryClient.setQueryData(['applicationConfig', saved.application], saved)
+      queryClient.invalidateQueries({ queryKey: ['applicationConfig', 'all'] })
     },
   })
 }