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/FreeVisitPrice.tsx

@@ -79,7 +79,7 @@ export default function FreeVisitPrice({ doctorUuid, readOnly = false }: { docto
       <label style={{ display: 'inline-flex', alignItems: 'center', gap: 10, fontSize: 13, cursor: 'pointer', marginTop: 16 }}>
         <span style={{
           position: 'relative', width: 42, height: 22, borderRadius: 999, flexShrink: 0,
-          background: required ? 'var(--primary)' : '#c4c4c4', transition: 'background .2s',
+          background: required ? 'var(--primary)' : 'var(--border-2)', transition: 'background .2s',
         }}>
           <input
             type="checkbox" checked={required} role="switch" aria-label="الزامی کردن هزینه ویزیت"
@@ -88,7 +88,7 @@ export default function FreeVisitPrice({ doctorUuid, readOnly = false }: { docto
           />
           <span style={{
             position: 'absolute', top: 2, insetInlineStart: required ? 22 : 2, width: 18, height: 18,
-            borderRadius: 999, background: '#fff', transition: 'inset-inline-start .2s', boxShadow: '0 1px 2px rgba(0,0,0,.2)',
+            borderRadius: 999, background: 'var(--surface)', transition: 'inset-inline-start .2s', boxShadow: '0 1px 2px rgba(0,0,0,.2)',
           }} />
         </span>
         الزامی کردن هزینه ویزیت