- BaseAgent.run(): catch httpx.ConnectError/ReadError/ConnectionError,
log 'Ollama disconnected: <error>' at ERROR level, then re-raise
- session.py: distinguish Ollama disconnects from other errors in
chat(), chat_with_tools(), continue_chat() — return specific message
'Ollama appears to be disconnected' instead of generic error
- 11 new tests covering all disconnect paths
