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/pages/EditSessionPage.tsx

@@ -42,20 +42,20 @@ export default function EditSessionPage() {
   return (
     <div className="fade-in" style={{ width: '100%' }}>
       <div style={{ display: 'flex', justifyContent: 'flex-start', marginBottom: 30 }}>
-        <div className="dark:text-[#A1A1A1]" style={{ display: 'flex', alignItems: 'center', gap: 8, color: '#6B7280', fontSize: 12, padding: '0 16px' }}>
-          <div onClick={() => nav(-1)} className="bg-white dark:bg-[#222433]" style={{ display: 'flex', alignItems: 'center', gap: 4, padding: '6px 8px', borderRadius: 12, cursor: 'pointer' }}>
+        <div style={{ display: 'flex', alignItems: 'center', gap: 8, color: 'var(--text-2)', fontSize: 12, padding: '0 16px' }}>
+          <div onClick={() => nav(-1)} className="bg-[var(--surface)]" style={{ display: 'flex', alignItems: 'center', gap: 4, padding: '6px 8px', borderRadius: 12, cursor: 'pointer' }}>
             <ArrowLeftPH style={{ width: 18, height: 18, rotate: '180deg' }} />
             <span>بازگشت</span>
           </div>
           <ArrowLeftD />
           <span>پرونده</span>
           <ArrowLeftD />
-          <span className="dark:text-[#D7D8ED]" style={{ color: '#111827' }}>{patientName}</span>
+          <span style={{ color: 'var(--text)' }}>{patientName}</span>
         </div>
       </div>
 
       <div style={{ width: '100%', display: 'flex', justifyContent: 'center' }}>
-        <div className="bg-white dark:bg-[#222433]" style={{ width: 748, maxWidth: '100%', padding: 24 }}>
+        <div className="bg-[var(--surface)]" style={{ width: 748, maxWidth: '100%', padding: 24 }}>
           <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', marginBottom: 12 }}>
             <h2 style={{ fontSize: 16, fontWeight: 700 }}>ویرایش مراجعه</h2>
             <button type="button" aria-label="بستن" onClick={() => nav(-1)}