fix(platform): register ai-diagnostics routes + wire 6 hidden sidebar pages

Phase 0 from DASHBOARD_UI_COVERAGE_ROADMAP:
- Register ai-diagnostics routes in server.ts (671-line module was never mounted)
- Add 6 hidden pages to admin sidebar-nav.tsx:
  Debug Sessions, Health Dashboard, Extraction, Experiments,
  Predictive, AI Diagnostics
- /users was already in sidebar (no change needed)
- Kill switch verified: already per-product via productId query param
- Admin sidebar now has 33 items (was 27)

dashboards/admin-web/src/components/sidebar-nav.tsx

@@ -33,6 +33,12 @@ import {
   ClipboardList,
   Beaker,
   Crosshair,
+  Bug,
+  HeartPulse,
+  FileSearch,
+  FlaskConical,
+  BrainCircuit,
+  TrendingDown,
 } from 'lucide-react';
 import { cn } from '@/lib/utils';
 import { useAuth } from '@/lib/auth-context';
@@ -59,10 +65,16 @@ const navItems = [
   { href: '/flags', label: 'Feature Flags', icon: Settings },
   { href: '/audit', label: 'Audit Log', icon: ScrollText },
   { href: '/actiontrail', label: 'ActionTrail', icon: Crosshair },
+  { href: '/experiments', label: 'Experiments', icon: FlaskConical },
+  { href: '/predictive/at-risk', label: 'Predictive', icon: TrendingDown },
   { href: '/ops', label: 'Mission Control', icon: Activity },
   { href: '/ops/client-logs', label: 'Client Logs', icon: FileText },
   { href: '/ops/telemetry-policies', label: 'Telemetry Policies', icon: Shield },
   { href: '/ops/ab-testing', label: 'A/B Testing', icon: Beaker },
+  { href: '/debug-sessions', label: 'Debug Sessions', icon: Bug },
+  { href: '/health-dashboard', label: 'Health Dashboard', icon: HeartPulse },
+  { href: '/extraction', label: 'Extraction', icon: FileSearch },
+  { href: '/ai-diagnostics', label: 'AI Diagnostics', icon: BrainCircuit },
   { href: '/feedback', label: 'User Feedback', icon: MessageSquare },
   { href: '/ops/secrets', label: 'Secrets Manager', icon: KeyRound },
   { href: '/settings', label: 'Settings', icon: Settings },

services/platform-service/src/server.ts

@@ -98,6 +98,7 @@ import { tenantRoutes } from './modules/tenants/routes.js';
 import { retentionRoutes } from './modules/retention/routes.js';
 import { backupRoutes } from './modules/backups/routes.js';
 import { apiVersioningRoutes } from './modules/api-versioning/routes.js';
+import aiDiagnosticsRoutes from './modules/ai-diagnostics/routes.js';
 import { initCosmosIfNeeded } from './lib/cosmos-init.js';
 import { config } from './lib/config.js';
 import { type JwtPayload, extractProductIdAsync } from './lib/request-context.js';
@@ -264,6 +265,9 @@ await app.register(retentionRoutes, { prefix: '/api' });
 await app.register(backupRoutes, { prefix: '/api' });
 await app.register(apiVersioningRoutes, { prefix: '/api' });
 
+// AI Diagnostics (NL query, LLM root-cause, error clustering)
+await app.register(aiDiagnosticsRoutes, { prefix: '/api' });
+
 // Event subscriptions + DLQ + replay
 await app.register(eventSubscriptionRoutes, { prefix: '/api' });
 // Agent executor + tool registry + scheduling + metrics