feat: wire remaining PostHog events across all key user actions (#111)

- export_generated: session copy, copy-for-ticket, download
- ai_feature_used: copilot, assistant chat, session-to-flow, KB accelerator, flow assist
- psa_connected: ConnectWise integration creation
- session_shared: share link creation
- flow_created: troubleshooting editor, procedural editor, session-to-flow

All 9 events from the product analytics plan are now fully wired.

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

frontend/src/components/session/ShareSessionModal.tsx

@@ -1,6 +1,7 @@
 import { useState, useEffect, useCallback } from 'react'
 import { Copy, Check, Globe, Users, Clock, Trash2, Link2 } from 'lucide-react'
 import type { SessionShare, SessionShareVisibility } from '@/types'
+import { analytics } from '@/lib/analytics'
 import { sessionsApi } from '@/api/sessions'
 import { buildSessionShareUrl, filterSharesForSession } from '@/lib/sessionShare'
 import { cn } from '@/lib/utils'
@@ -122,6 +123,7 @@ export function ShareSessionModal({ sessionId, sessionLabel, isOpen, onClose }:
         expires_at,
       })
       setShares([newShare, ...shares])
+      analytics.sessionShared({ session_id: sessionId, visibility })
       toast.success('Share link generated')
       setShareName('')
       setExpirationPreset('never')