Add Peaksea themes for macOS Ghostty

[adihex]

Summary

• add portable Peaksea Dark and Peaksea Light user themes for macOS Ghostty
• follow macOS appearance automatically with Ghostty's supported light/dark theme selector
• make the terminal fully opaque with blur disabled
• allow each theme to provide its own cursor colors
• document that Ghostty does not support WezTerm's custom per-window light/dark toggle

Opacity

• background-opacity = 1
• background-opacity-cells = false
• background-blur = false
• existing unfocused-split-opacity = 0.85 and cursor-opacity = 0.85 are preserved

Validation

Validated byte-for-byte repository candidates with Ghostty 1.3.1 under a fresh isolated temporary HOME:

• main config and both standalone theme files: ghostty +validate-config exited 0 with no diagnostics
• ghostty +list-themes --plain --path discovered both themes as user themes
• ghostty +show-config --changes-only resolved current macOS light appearance to the exact Peaksea Light background, foreground, cursor, selection, and ANSI palette
• SHA-256 matches authoritative local files:
  • config: 6b68fb9b4b97b8b17fe20314b8eb043aeca537dbab8b3fd2aba7c72796545cbb
  • Peaksea Dark: e5cf9bffad9bbede7dd216304fbdf9e550a58a22cdec3c80403bff84a4295f26
  • Peaksea Light: 9fdbeb01241572a12a50c2b54df43c80c6d505888042bfc26ef6e0d1aeeb6245
• staged personal-path and secret scans found nothing; git diff --cached --check passed

Ghostty follows system appearance rather than providing WezTerm's per-window CMD+SHIFT+L callback.