Add Claude bot chat endpoint

[nickmeinhold]

Description

Add a WebSocket message type and handler for players to chat with the Claude bot.

Acceptance Criteria

• Define a new message type for bot chat (e.g., bot_chat_request, bot_chat_response)
• Add message handler in ClientConnectionsService
• Integrate with Claude API for generating responses
• Return bot responses to the requesting client

Technical Considerations

• Need to add Claude API key configuration
• Consider rate limiting per player
• May need conversation context/history per player

Related

• Bot is currently defined in bot_user.dart
• Client will need corresponding UI (tracked in tech_world repo)