W7 of the oak task list. OakTheme::olive_dark/olive_light translate oak's
palette.ini files into a structured theme (window/base/alternate/accent/
link/disabled plus a derived border). apply_theme swaps gpui's GlobalColors
so every widget reading cx.default_colors() re-themes immediately, and
stores the full theme in a ThemeGlobal. Palette contrast and mapping are
unit-tested, with a gpui::test verifying the runtime switch;
examples/themes.rs toggles between the two themes live. 101 widget tests
pass.
Mike-Solar
098d422628