feat: upgrade terminal to xterm.js + WebSocket
- Rewrite terminal.js: xterm.js Terminal per tab, WebSocket per connection
- Light theme terminal (Lumina: white bg, blue cursor, proper ANSI colors)
- Alpine.js keeps tab management, xterm.js handles rendering
- Each tab gets its own WebSocket to /terminal/ws/:hostID
- Mock handler iterates chars (fixes multi-char xterm.js messages)
- Sync mock commands with React template (help, ls, docker ps, etc.)
- Add xterm.css custom scrollbar styles
- terminal_content.html: xterm containers with Alpine show/hide per tab
swanadiva
ef4e44984b