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/copilot/CopilotPanel.tsx

@@ -2,6 +2,7 @@ import { useState, useRef, useEffect, useCallback } from 'react'
 import { X, Send, Sparkles, Loader2 } from 'lucide-react'
 import { MarkdownContent } from '@/components/ui/MarkdownContent'
 import { copilotApi } from '@/api/copilot'
+import { analytics } from '@/lib/analytics'
 import { SuggestedFlowCard } from '@/components/assistant/SuggestedFlowCard'
 import type { CopilotMessage, SuggestedFlow } from '@/types/copilot'
 
@@ -32,6 +33,7 @@ export function CopilotPanel({ isOpen, onClose, treeId, sessionId, currentNodeId
         current_node_id: currentNodeId,
       })
       setConversationId(response.conversation_id)
+      analytics.aiFeatureUsed({ feature: 'copilot' })
       setMessages([{ role: 'assistant', content: response.greeting }])
     } catch {
       setMessages([{ role: 'assistant', content: 'Failed to start copilot. Please try again.' }])