Restricting colors and fonts to a brand palette

[gwhthompson]

We use the editor inside a Laravel app as the newsletter builder for a magazine. The person writing the emails isn't a designer, and the brand is a fixed palette plus two typefaces. Right now there's no way to keep them inside that: every color picker has the wheel and hex input, and the seven built-in fonts always show up next to customFonts.

Two options I'd like to add:

1. colors: { presets?: string[], allowCustom?: boolean }. Presets render as a grid of chips in the picker popover. With allowCustom: false the wheel and hex input are removed and the chips are all you get.
2. fonts.builtIns?: boolean | string[]. false removes the built-ins from the picker, an array keeps a subset. Only the picker list changes; content already using an excluded font still renders with its normal fallback stack.

Later I'd also like per-field presets on CustomBlockColorField, so a button color field can offer just the accent pair, but that can wait until the base is in.

I've built both already: unit tests, docs (en + de), changesets, a playground scenario for each, and a Playwright spec. Nothing changes when the options aren't set. I can open the PRs now, or change names or placement first if you'd do it differently.

Here's the locked picker in the playground (Event Invitation template with a six-color palette and allowCustom: false):

[orkhanahmadov]

Thank you @gwhthompson for the useful idea and clean implementation.

Both PRs are merged and I just released version 0.19.0 with both changes included.

Thank you again, and keep good ideas coming! 👍