feat(ai-session): add Phase 2 PSA integration, escalation handoff, and session management

Phase 2 of the FlowPilot-First Pivot connecting AI sessions to ConnectWise PSA:

Slice 1 — PSA Ticket Intake:
- FlowPilotEngine accepts psa_ticket intake with graceful CW API fallback
- Ticket picker on intake screen (refactored TicketPickerModal for dual-mode)
- Ticket context card in session sidebar

Slice 2 — Auto Documentation Push:
- PSA documentation service with resolution/escalation note formatting
- Time entry creation via new ConnectWise provider method
- Automatic retry scheduler (APScheduler, 5min interval, 3 retries)
- PSA push status indicators in frontend with manual retry button
- Member mapping warning when CW member not mapped

Slice 3 — Session Pause/Resume & Escalation Handoff:
- Pause/resume endpoints for same-engineer session bookmarking
- Escalation flow: requesting_escalation status, self-escalation blocked
- Enhanced escalation package with LLM-generated hypotheses/suggestions
- Pickup endpoint with continue/fresh resume modes and briefing step
- Escalation queue (sidebar nav + dedicated page)
- SessionBriefing component with continue/fresh choice UI
- EscalateModal with PSA-aware button text

Slice 4 — Mid-Session Ticket Linking:
- Link ticket retroactively with context injection into system prompt
- Link Ticket button in session sidebar

Slice 5 — FlowPilot PSA Settings:
- Settings tab on IntegrationsPage with 7 configurable options
- Stored as flowpilot_settings JSONB on PsaConnection

Database: 2 migrations (flowpilot_settings, psa_post_log changes, status constraint)

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

frontend/src/router.tsx

@@ -46,6 +46,7 @@ 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 EscalationQueuePage = lazy(() => import('@/pages/EscalationQueuePage'))
 const KBAcceleratorPage = lazy(() => import('@/pages/KBAcceleratorPage'))
 const GuidesHubPage = lazy(() => import('@/pages/GuidesHubPage'))
 const GuideDetailPage = lazy(() => import('@/pages/GuideDetailPage'))
@@ -172,6 +173,7 @@ export const router = sentryCreateBrowserRouter([
       { path: 'flow-assist', element: page(FlowAssistPage) },
       { path: 'pilot', element: page(FlowPilotSessionPage) },
       { path: 'pilot/:sessionId', element: page(FlowPilotSessionPage) },
+      { path: 'escalations', element: page(EscalationQueuePage) },
       { path: 'guides', element: page(GuidesHubPage) },
       { path: 'guides/:slug', element: page(GuideDetailPage) },
       // Admin routes