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/api/tracker/domain/src/lib/project/project-settings.spec.ts

@@ -84,6 +84,25 @@ describe('Project settings', () => {
     );
   });
 
+  it('takes a palette colour or any #rrggbb, and nothing else', () => {
+    const project = newProject();
+    const settings = defaultProjectSettings();
+    settings.statuses[0].color = '#7c3aed';
+    settings.issueTypes[0].color = '#0EA5E9';
+    project.updateSettings('owner', settings);
+    expect(project.workflow.status(settings.statuses[0].id)?.color).toBe(
+      '#7c3aed',
+    );
+
+    for (const color of ['purple', '#abc', 'url(x)', '#7c3aedff']) {
+      const bad = defaultProjectSettings();
+      bad.statuses[0].color = color as never;
+      expect(() => project.updateSettings('owner', bad)).toThrow(
+        /Color no válido/,
+      );
+    }
+  });
+
   it('archives values instead of deleting them', () => {
     const project = newProject();
     const settings = defaultProjectSettings();