feat(terminal): overhaul with xterm.js, raw TTY streaming, and dynamic resizing ...

- Replaced simulated terminal with xterm.js for native emulation
- Implemented raw TTY byte streaming over WebSockets
- Added support for persistent shell sessions and window resizing (ioctl TIOCSWINSZ)
- Improved SkillManager with a transparent TTY bypass to prevent thread pool saturation
- Added periodic heartbeat-based latency monitoring (RTT)
- Fixed skill_config parsing crash in AI Hub registry
- Enabled auto-scrolling and terminal-to-PTY grid synchronization