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/types/api.ts

@@ -116,3 +116,31 @@ export interface UsageHistoryResponse {
   window: string
   points: UsageHistoryPoint[]
 }
+
+/** One MCP-server or agent target's current-window request counters (admin.go: adminTargetCountersView) — requests only, no tokens or cost. */
+export interface AdminTargetCountersView {
+  requestsPerMinute: number
+  requestsPerDay: number
+  requestsPerMonth: number
+}
+
+/**
+ * One configured MCP server's or A2A agent's row in GET /admin/api/targets
+ * (admin.go: adminTargetView). Access is the group names actually allowed
+ * to reach this target, computed server-side via the same matching authz
+ * enforcement uses — undefined/empty means every configured group can
+ * reach it ("empty meaning all", mirroring AdminUsageEntryView's own
+ * providers/models/mcpServers/agents convention above).
+ */
+export interface AdminTargetView {
+  name: string
+  url: string
+  access?: string[]
+  counters: AdminTargetCountersView
+}
+
+/** GET /admin/api/targets (admin.go: adminTargetsResponse). */
+export interface AdminTargetsResponse {
+  mcpServers: AdminTargetView[]
+  agents: AdminTargetView[]
+}