Implement comprehensive dark/light mode overhaul for admin panel

- Refactor color palette in `ui-design-spec.md` to utilize CSS variables exclusively, eliminating fixed hex values and Tailwind utility classes.
- Complete dark mode implementation in `uiStore.ts`, ensuring proper theme application via `applyTheme()` and `applyBrand()`.
- Create `admin-theme-dark-light-audit.md` to document the transition process, outlining issues with inline styles and fixed colors.
- Introduce `theme-tokens.test.ts` to enforce rules against fixed hex colors and ensure compliance with the design system.
- Update various components and styles to replace inline styles and fixed colors with CSS variables, ensuring consistent theming across light and dark modes.
- Ensure all changes maintain visual integrity in both light and dark modes, with a focus on accessibility and contrast standards.

assets/admin/components/dashboard/dashboardIcons.tsx

@@ -68,10 +68,10 @@ export function CalendarIcon() {
 }
 
 /** فلش رو به پایین — status chip chevron (source: ArrowDownBlueP) */
-export function ChevronDownIcon({ color = '#5559CE' }: { color?: string }) {
+export function ChevronDownIcon({ color = 'currentColor' }: { color?: string }) {
   return (
-    <svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 20 20" fill="none">
-      <path d="M16.6004 7.4585L11.1671 12.8918C10.5254 13.5335 9.47539 13.5335 8.83372 12.8918L3.40039 7.4585" stroke={color} strokeWidth="1.5" strokeMiterlimit="10" strokeLinecap="round" strokeLinejoin="round" />
+    <svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 20 20" fill="none" style={{ color }}>
+      <path d="M16.6004 7.4585L11.1671 12.8918C10.5254 13.5335 9.47539 13.5335 8.83372 12.8918L3.40039 7.4585" stroke="currentColor" strokeWidth="1.5" strokeMiterlimit="10" strokeLinecap="round" strokeLinejoin="round" />
     </svg>
   );
 }