Support WordPress Font Library fonts in Style Manager font controls

[georgeolaru]

Summary

LT users want to manage custom or self-hosted fonts through WordPress core (or compatible font providers) and have those fonts show up in Style Manager font controls, so Fonto becomes optional instead of mandatory.

Why

A recent Felt LT support request asked for native WordPress font management, or at least compatibility with another font manager, because custom fonts uploaded outside Fonto do not appear in LT typography pickers today.

Current behavior

• LT typography controls are defined as Style Manager font fields in pixelgrade/anima (inc/integrations/style-manager/fonts.php).
• Style Manager currently builds its font sources from:
  • style_manager/third_party_fonts
  • style_manager/cloud_fonts
  • style_manager/theme_fonts
  • style_manager/system_fonts
  • bundled Google fonts
• pixelgrade/fonto integrates by pushing its fonts into style_manager/third_party_fonts.
• There is no equivalent provider for WordPress core Font Library or core-registered custom fonts, so fonts managed outside Fonto are invisible to SM controls.

Requested outcome

Add a WordPress-core font provider to Style Manager so SM font controls and loaders can consume fonts registered outside Fonto.

Acceptance criteria

• Fonts added through the WordPress Font Library appear in Style Manager font controls.
• Selected core-managed fonts load correctly in the frontend, Customizer, and block editor.
• Variant metadata is normalized into the same structure SM already expects (family, variants, source/load info).
• Compatible third-party plugins that register fonts through core APIs should work automatically where possible, without hardcoding a one-off integration per plugin.
• Fonto remains supported, but it is no longer the only way to use custom fonts in LT themes.

Implementation notes

Relevant code paths:

• src/Customize/Fonts.php
• src/_js/utils/maybe-load-font-family.js
• src/Screen/EditWithBlocks.php

This likely pairs with a companion pixelgrade/anima change so LT themes stop suppressing the native Font Library workflow once SM can consume those fonts.