fix: address CodeRabbitAI review comments for conversation history

- Fix duplicate onConversationCreated callbacks by tracking activeConversationId
- Fix history loss when switching conversations with Map-based deduplication
- Disable input while conversation is loading to prevent message routing issues
- Gate WebSocket debug logs behind DEV flag (import.meta.env.DEV)
- Downgrade server logging from info to debug level for reduced noise
- Fix .gitignore prefixes for playwright paths (ui/playwright-report/, ui/test-results/)
- Remove debug console.log from ConversationHistory.tsx
- Add staleTime (30s) to single conversation query for better caching
- Increase history message cap from 20 to 35 for better context
- Replace fixed timeouts with condition-based waits in e2e tests

server/services/assistant_chat_session.py

@@ -345,6 +345,8 @@ class AssistantChatSession:
             history = get_messages(self.project_dir, self.conversation_id)
             # Exclude the message we just added (last one)
             history = history[:-1] if history else []
+            # Cap history to last 35 messages to prevent context overload
+            history = history[-35:] if len(history) > 35 else history
             if history:
                 # Format history as context for Claude
                 history_lines = ["[Previous conversation history for context:]"]