Theme · Editing: a theme laid open, and an owner's palette per mode

settings::ThemeEditor lays a theme open: density, corners, text size,
high contrast and reduced motion, then twelve colors of the mode shown,
each a swatch that opens a picker beside its hex; each change hands the
owner a whole draft. Theme::set_palette takes an owner's palette per
mode, the colors fading to it when the mode shows; Theme::palette names
the palette the shown mode fades to; Palette::token_mut and
Syntax::token_mut reach a color by its field's name. The gallery's
theme page applies the editor to the whole gallery live, with a way
back to Ely's theme.

src/forms/mod.rs

@@ -56,6 +56,7 @@ pub use checked::{EmailInput, UrlInput, is_email, is_url};
 pub use chips::ChoiceChips;
 pub use code::{CodeInput, JsonInput, code_highlights, json_highlights};
 pub(crate) use code::{Kind, lex};
+pub(crate) use color::hex;
 pub use color::{ColorPalette, ColorPicker, ColorSwatch, EyeDropper, GradientEditor, GradientStop};
 pub use combobox::Combobox;
 pub use date::{