feat: statuses and ticket types take any colour from a colour picker

Settings shows a native colour picker (the palette as suggestions)
instead of the list of eleven names. The API takes a palette name, as
before, or any #rrggbb; picking a palette colour still saves its name,
so it keeps its hand-made dark version. A free colour gets one variant
per theme, computed with the `color` library (moved towards white or
black until it contrasts 3:1 with the surface) and applied with
light-dark(): a pale yellow darkens on white, a navy lightens on dark.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

libs/web/tracker/domain/src/lib/models/workflow.ts

@@ -14,7 +14,8 @@ export const SETTING_COLORS = [
   'red',
   'pink',
 ] as const;
-export type SettingColor = (typeof SETTING_COLORS)[number];
+/** A palette name (follows the theme) or any `#rrggbb`. */
+export type SettingColor = (typeof SETTING_COLORS)[number] | `#${string}`;
 
 /** Icons a ticket type can use. */
 export const TYPE_ICONS = [