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/components/layout/Sidebar.tsx

@@ -3,7 +3,7 @@ import { useLocation } from 'react-router-dom'
 import {
   LayoutGrid, Network, Wrench, Clock, FileOutput, BarChart3,
   Settings, PanelLeftClose, PanelLeftOpen, MessageSquareText,
-  BookOpen, Lightbulb, Code2, Library, Brain, WandSparkles, Sparkles,
+  BookOpen, Lightbulb, Code2, Library, Brain, WandSparkles, Sparkles, AlertTriangle,
 } from 'lucide-react'
 import { cn } from '@/lib/utils'
 import { useUserPreferencesStore } from '@/store/userPreferencesStore'
@@ -86,6 +86,7 @@ export function Sidebar() {
             <NavItem href="/pilot" icon={Sparkles} label="New Session" iconColor={NAV_COLORS.dashboard} collapsed />
             <NavItem href="/" icon={LayoutGrid} label="Dashboard" iconColor={NAV_COLORS.dashboard} collapsed />
             <NavItem href="/sessions" icon={Clock} label="Sessions" badge={stats?.active_count || undefined} iconColor={NAV_COLORS.sessions} collapsed />
+            <NavItem href="/escalations" icon={AlertTriangle} label="Escalations" iconColor="text-amber-400" collapsed />
             <NavItem href="/trees" icon={Network} label="All Flows" matchPaths={['/trees', '/flows']} iconColor={NAV_COLORS.flows} collapsed />
             <NavItem href="/assistant" icon={Brain} label="FlowPilot" iconColor={NAV_COLORS.flowPilot} collapsed />
             <NavItem href="/scripts" icon={Code2} label="Script Library" iconColor={NAV_COLORS.scripts} collapsed />
@@ -135,6 +136,7 @@ export function Sidebar() {
               Resolve
             </div>
             <NavItem href="/sessions" icon={Clock} label="Sessions" badge={stats?.active_count || undefined} iconColor={NAV_COLORS.sessions} />
+            <NavItem href="/escalations" icon={AlertTriangle} label="Escalations" iconColor="text-amber-400" />
             <NavItem
               href="/trees"
               icon={Network}