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/pages/ProceduralEditorPage.tsx

@@ -1,6 +1,7 @@
 import { useEffect, useState, useCallback } from 'react'
 import { useParams, useNavigate, useSearchParams } from 'react-router-dom'
 import { Save, ArrowLeft, ListOrdered, Wrench, Settings, FileText, Calendar, Sparkles, Layers } from 'lucide-react'
+import { analytics } from '@/lib/analytics'
 import { Button } from '@/components/ui/Button'
 import { treesApi } from '@/api/trees'
 import { useProceduralEditorStore } from '@/store/proceduralEditorStore'
@@ -222,6 +223,7 @@ export function ProceduralEditorPage() {
         toast.success(`${flowLabel} saved`)
       } else {
         const created = await treesApi.create(payload)
+        analytics.flowCreated({ flow_type: payload.tree_type || 'procedural', method: 'manual' })
         markSaved()
         toast.success(`${flowLabel} created`)
         navigate(`/flows/${created.id}/edit`, { replace: true })