Grew /admin/theme from colours-only to a full theme editor, all applied
live via website_settings + ThemeVars:
- Typography: body font (10 web-safe + Google options; Google fonts load
via an injected <link>) and H1/H2/H3 sizes (globals.css now reads
--size-heading-* vars).
- Buttons & links: secondary/danger button colours + link/link-hover.
- Custom CSS: a raw textarea injected after the theme variables (staff-
trusted), for anything the controls don't cover.
- Presets: 6 → 13 (added Galaxy, Royal, Cyberpunk, Neon, Coffee, Arctic,
Christmas). ThemeVars now injects all the new vars + the font link.
Verified live (prod, amx_test): saved font=mono / H1=44px / custom CSS →
the public home reflected --font-family "Courier New", --size-heading-h1
44px and the injected rule; reverted the test settings. tsc 0,
vitest 49/49, next build 0.