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.

plans/index.md

@@ -11,7 +11,7 @@ went sideways, open an investigation.
 | 2026-07-05 | [Oikos Prometheus LXC](2026-07-05-oikos-prometheus-lxc.md) | Planned |
 | 2026-07-08 | [Plan vs implementation cross-reference](2026-07-08-plan-implementation-audit.md) | Planned |
 | 2026-07-08 | [Oikos gaps, broken things, and improvements](2026-07-08-oikos-gaps-and-improvements.md) | Planned |
-| 2026-07-08 | [Control room web UI](2026-07-08-control-room-webui.md) | Planned |
+| 2026-07-08 | [Control room web UI](2026-07-08-control-room-webui.md) | In Progress |
 | 2026-07-08 | [Nomos resident agent (renames Hermes)](2026-07-08-nomos-resident-agent.md) | In Progress |
 
 ## Done