Implements a persistent browser management system that allows running a single shared browser instance
that can be reused across multiple crawler sessions. Key changes include:
- Added browser_mode config option with 'builtin', 'dedicated', and 'custom' modes
- Implemented builtin browser management in BrowserProfiler
- Added CLI commands for managing builtin browser (start, stop, status, restart, view)
- Modified browser process handling to support detached processes
- Added automatic builtin browser setup during package installation
BREAKING CHANGE: The browser_mode config option changes how browser instances are managed
