Changes:
- Fix JSON path for session logs: now reads from context_window.conversation_history
(with fallback to messages for backwards compatibility)
- Remove 500-character truncation to show full summary
- Add termimad dependency for terminal markdown rendering
- Display summary with proper markdown formatting (headers, bold, code, lists)
The extract_session_summary() function was looking for messages at the wrong
JSON path. Session logs store conversation history at context_window.conversation_history,
not at the top-level messages key.
30bb63715e