feat: disable text styling in --no-interactive mode

Automatically disable ANSI color codes and styling when running in
non-interactive mode to ensure clean output for programmatic usage.

- Add session-scoped enable_styling flag to ChatSession
- Create conditional styling macros (execute_conditional!, queue_conditional!)
- Implement IsStyling trait for crossterm styling commands
- Replace all styling calls with conditional macros except for spinner
- Remove response prefix ("> ") in non-interactive mode
- Add raw text output path bypassing markdown parser when styling disabled
- Text styling is automatically disabled when --no-interactive flag is used
- Maintains clean output for programmatic usage while preserving colors in interactive mode

Author: StoneDot