feat: migrate UI to @cameleer/design-system, add backend endpoints

Backend:
- Add agent_events table (V5) and lifecycle event recording
- Add route catalog endpoint (GET /routes/catalog)
- Add route metrics endpoint (GET /routes/metrics)
- Add agent events endpoint (GET /agents/events-log)
- Enrich AgentInstanceResponse with tps, errorRate, activeRoutes, uptimeSeconds
- Add TimescaleDB retention/compression policies (V6)

Frontend:
- Replace custom Mission Control UI with @cameleer/design-system components
- Rebuild all pages: Dashboard, ExchangeDetail, RoutesMetrics, AgentHealth,
  AgentInstance, RBAC, AuditLog, OIDC, DatabaseAdmin, OpenSearchAdmin, Swagger
- New LayoutShell with design system AppShell, Sidebar, TopBar, CommandPalette
- Consume design system from Gitea npm registry (@cameleer/design-system@0.0.1)
- Add .npmrc for scoped registry, update Dockerfile with REGISTRY_TOKEN arg

CI:
- Pass REGISTRY_TOKEN build-arg to UI Docker build step

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

ui/src/index.css

@@ -0,0 +1,18 @@
+@import url('https://fonts.googleapis.com/css2?family=DM+Sans:ital,opsz,wght@0,9..40,100..1000;1,9..40,100..1000&family=JetBrains+Mono:wght@400;500;600&display=swap');
+
+:root {
+  font-family: 'DM Sans', system-ui, sans-serif;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}
+
+*,
+*::before,
+*::after {
+  box-sizing: border-box;
+  margin: 0;
+}
+
+html, body, #root {
+  height: 100%;
+}