Monitor additional Ghostty actions (config reload, mouse shape)

[mvbmir]

Summary

Ghostty fires several action callbacks that limux currently ignores. Hooking into them would improve responsiveness and correctness.

Unmonitored Actions

Action Tag	Name	What It Does
46	GHOSTTY_ACTION_RELOAD_CONFIG	Fires when Ghostty config is reloaded. Limux should re-read relevant settings (opacity, font, colors)
47	GHOSTTY_ACTION_CONFIG_CHANGE	Individual config key changes. Could enable live-updating specific UI elements
35	GHOSTTY_ACTION_MOUSE_SHAPE	Mouse cursor shape requests from the terminal. Currently ignored, so cursor doesn't change for e.g. links
54	GHOSTTY_ACTION_SHOW_CHILD_EXITED	Child process exit notification. Could show a "process exited" overlay like Ghostty native does
45	GHOSTTY_ACTION_COLOR_CHANGE	Color scheme changes. Tracked in #9

Impact

• Config reload is important for users who edit ghostty config and expect changes to apply without restarting limux
• Mouse shape is a polish item but noticeable (cursor stays as default arrow over links in TUI apps)
• Child exited notification would prevent confusing blank terminals when a shell crashes