feat(ai-session): add FlowPilot AI-powered troubleshooting sessions

Implements Phase 1 of the FlowPilot-First pivot — the core AI session
experience where engineers describe a problem and FlowPilot guides them
through structured diagnosis with selectable options, free-text escape
hatches, and auto-generated documentation on resolution.

Backend: AISession + AISessionStep models, FlowPilot Engine (LLM
orchestration with structured JSON output), Flow Matching Engine v1
(semantic + keyword + recency scoring), 8 API endpoints with auth,
rate limiting, and AI quota enforcement.

Frontend: Intake screen, conversational session view with sidebar,
step cards with options/actions/resolution suggestions, resolve/escalate
modals, documentation view with rating, session history integration,
and /pilot route with sidebar navigation.

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

frontend/src/router.tsx

@@ -45,6 +45,7 @@ const ScriptLibraryPage = lazy(() => import('@/pages/ScriptLibraryPage'))
 const ScriptManagePage = lazy(() => import('@/pages/ScriptManagePage'))
 const AssistantChatPage = lazy(() => import('@/pages/AssistantChatPage'))
 const FlowAssistPage = lazy(() => import('@/pages/FlowAssistPage'))
+const FlowPilotSessionPage = lazy(() => import('@/pages/FlowPilotSessionPage'))
 const KBAcceleratorPage = lazy(() => import('@/pages/KBAcceleratorPage'))
 const GuidesHubPage = lazy(() => import('@/pages/GuidesHubPage'))
 const GuideDetailPage = lazy(() => import('@/pages/GuideDetailPage'))
@@ -169,6 +170,8 @@ export const router = sentryCreateBrowserRouter([
       { path: 'kb-accelerator', element: page(KBAcceleratorPage) },
       { path: 'assistant', element: page(AssistantChatPage) },
       { path: 'flow-assist', element: page(FlowAssistPage) },
+      { path: 'pilot', element: page(FlowPilotSessionPage) },
+      { path: 'pilot/:sessionId', element: page(FlowPilotSessionPage) },
       { path: 'guides', element: page(GuidesHubPage) },
       { path: 'guides/:slug', element: page(GuideDetailPage) },
       // Admin routes