feat(webui): MCP & Agents admin tab

New 'MCP & Agents' tab (after Charts) fed by GET /admin/api/targets:
two Card panels, each a sortable DataTable (reusing DataTable/
SortHeaderButton — no hand-rolled table markup) listing configured
MCP servers and agents with name, url (muted, truncated with a title
tooltip), access (Badge per allowed group, muted 'All groups' when
unrestricted — the same idiom UsageView's own group Access block
already uses), and req/min, req/day, req/month.

- types/api.ts: AdminTargetCountersView/AdminTargetView/
  AdminTargetsResponse matching admin.go's JSON exactly.
- stores/dashboard.ts: targets fetched in the SAME Promise.all/5s
  poll as overview and usage — one store, one timer, not a third.
- lib/target-columns.ts: shared ColumnDef set both DataTables use.
- components/TargetsView.vue: SearchInput + useSearchQuery name
  filter (inline matching, mirroring ProvidersView's own single-field
  aliasMatches — not every filter needs a lib/*-search.ts module).

webui/src/stores/dashboard.ts

@@ -2,23 +2,26 @@ import { defineStore } from 'pinia'
 
 import { AdminApiError, adminFetch } from '@/lib/api'
 import { useAuthStore } from '@/stores/auth'
-import type { AdminOverviewResponse, AdminUsageResponse } from '@/types/api'
+import type { AdminOverviewResponse, AdminTargetsResponse, AdminUsageResponse } from '@/types/api'
 
-/** How often the Providers/Usage views poll (matches the replaced vanilla-JS page). */
+/** How often the Providers/Usage/Targets views poll (matches the replaced vanilla-JS page). */
 const POLL_MS = 5000
 
 /**
- * useDashboardStore polls GET /admin/api/overview and GET /admin/api/usage
- * together every POLL_MS, feeding the Providers and Usage views (the store's
- * own `overview` field keeps the backend's name — see ProvidersView.vue's
- * doc comment for the UI-label/API-name split). A single
- * store (not two) because both routes are always fetched together — the
- * old vanilla-JS page's own Promise.all([overview, usage]) pattern.
+ * useDashboardStore polls GET /admin/api/overview, GET /admin/api/usage,
+ * and GET /admin/api/targets together every POLL_MS, feeding the
+ * Providers, Usage, and MCP & Agents views (the store's own `overview`
+ * field keeps the backend's name — see ProvidersView.vue's doc comment
+ * for the UI-label/API-name split). A single store (not three) because
+ * every route is always fetched together — the old vanilla-JS page's own
+ * Promise.all([overview, usage]) pattern, extended to targets (Feature B,
+ * v0.21) rather than given its own separate poll timer.
  */
 export const useDashboardStore = defineStore('dashboard', {
   state: () => ({
     overview: null as AdminOverviewResponse | null,
     usage: null as AdminUsageResponse | null,
+    targets: null as AdminTargetsResponse | null,
     lastUpdated: null as Date | null,
     error: '',
     timer: undefined as ReturnType<typeof setInterval> | undefined,
@@ -28,12 +31,14 @@ export const useDashboardStore = defineStore('dashboard', {
       const auth = useAuthStore()
       if (!auth.isAuthenticated) return
       try {
-        const [overview, usage] = await Promise.all([
+        const [overview, usage, targets] = await Promise.all([
           adminFetch<AdminOverviewResponse>('/admin/api/overview'),
           adminFetch<AdminUsageResponse>('/admin/api/usage'),
+          adminFetch<AdminTargetsResponse>('/admin/api/targets'),
         ])
         this.overview = overview
         this.usage = usage
+        this.targets = targets
         this.lastUpdated = new Date()
         this.error = ''
       } catch (err) {