feat(theme): per-app accent: pm gives window manifest accent before app runs (display ACCENT, refused after BUFFER); theme::with_accent keeps hue, shifts lightness until contrast passes, else theme accent; tally pink

crates/types/src/display.rs

@@ -108,6 +108,11 @@ pub mod window {
     /// the default) is now in use; `MALFORMED` if there is none by that
     /// name.
     pub const SET_THEME: usize = 11;
+    /// Through a window, before anyone has asked for its buffer (so by
+    /// its launcher, before the app runs) and once: word 1 the app's
+    /// accent, `0xrrggbb`. The theme the window is handed carries it where
+    /// it passes contrast (`theme::with_accent`).
+    pub const ACCENT: usize = 12;
     /// The event (in place of an input event's tag) every window gets when
     /// the theme changes: ask for it again.
     pub const THEME_CHANGED: usize = 16;