When a project is loaded via /project, the prompt now shows:
agent_name |[project_name]>
where the |[project_name]> part is displayed in blue.
Examples:
- Default: g3>
- With project: g3 |[myapp]>
- Agent mode: butler>
- Agent + project: butler |[myapp]>
The prompt automatically resets when /unproject is called.
Added build_prompt() function with 7 unit tests covering all prompt states.