## Summary

Make GPUI's font suggestions reflect the platform text system's actual
font inventory, including fonts loaded by the application, rather than
appending hardcoded fallback candidates.

The appended names could be unavailable on the current platform.

The downside of this is that virtual aliases such as `.SystemUIFont`,
`.ZedMono`, and `.ZedSans` are no longer injected into suggestions;
existing settings using those aliases still resolve as before, they just
won't be shown in the settings UI anymore.

Release Notes:

- Fixed font suggestions listing unavailable fallback fonts and internal
font aliases.