feat(ui): M4 — agent activity, knowledge search, audit, correlation grouping

Add three new pages completing the control-room web UI:
- Agent activity: polls /agent-activity every 5s, filterable by type/agent
- Knowledge search: FTS over /knowledge/search with snippet + entity links
- Audit trail: browseable audit log with actor/action/entity filters

Enhanced live events page with correlation-id clustering (Groups toggle).
Added fetchAgentActivity/searchKnowledge/fetchAudit to the API client.
11 nav items now cover all planned control-room views.

web/src/lib/components/ui/select/index.ts

@@ -0,0 +1,37 @@
+import Root from "./select.svelte";
+import Group from "./select-group.svelte";
+import Label from "./select-label.svelte";
+import Item from "./select-item.svelte";
+import Content from "./select-content.svelte";
+import Trigger from "./select-trigger.svelte";
+import Separator from "./select-separator.svelte";
+import ScrollDownButton from "./select-scroll-down-button.svelte";
+import ScrollUpButton from "./select-scroll-up-button.svelte";
+import GroupHeading from "./select-group-heading.svelte";
+import Portal from "./select-portal.svelte";
+
+export {
+	Root,
+	Group,
+	Label,
+	Item,
+	Content,
+	Trigger,
+	Separator,
+	ScrollDownButton,
+	ScrollUpButton,
+	GroupHeading,
+	Portal,
+	//
+	Root as Select,
+	Group as SelectGroup,
+	Label as SelectLabel,
+	Item as SelectItem,
+	Content as SelectContent,
+	Trigger as SelectTrigger,
+	Separator as SelectSeparator,
+	ScrollDownButton as SelectScrollDownButton,
+	ScrollUpButton as SelectScrollUpButton,
+	GroupHeading as SelectGroupHeading,
+	Portal as SelectPortal,
+};