Create Ghostty help/cheatsheet page

[jangroth]

Create a reference page (or inline comment block in the config) documenting Ghostty features worth knowing.

Motivation

Titlebar is disabled (macos-titlebar-style = hidden), so window management shortcuts are easy to forget.

Must document

• Moving windows without titlebar: Cmd+drag anywhere in the window background
• Any other keyboard shortcuts for window management (resize, position)

Nice to have

Other Ghostty-specific features worth documenting (exclude anything tmux handles — splits, tabs, session management):

• URL opening / click handling
• Font size adjustment shortcuts
• Config hot-reload behaviour
• Quick terminal / visor mode (if available)
• Theme switching
• Scrollback behaviour / search

Format

Either a files/ghostty/HELP.md cheatsheet, or a comment block at the top of files/ghostty/config.