Story Updates:
- Unified model dropdown with section headers (Anthropic, Ollama)
- Auto-detect provider from model name (claude-* prefix)
- API key prompt on first Claude model use
- Secure storage in OS keychain via keyring crate
- 200k token context window for Claude models
Spec Updates (AI_INTEGRATION.md):
- Document Anthropic provider implementation
- Anthropic API protocol (SSE streaming, tool format)
- Tool format conversion between internal and Anthropic formats
- API key storage in OS keychain
- Unified dropdown UI flow
Spec Updates (STACK.md):
- Add keyring crate for secure API key storage
- Add eventsource-stream for Anthropic SSE streaming
- Document automatic provider detection
- Update API key management approach
