feat: Linear-style UI redesign with improved mobile experience

Major changes:
- Redesign cabinet with Linear-style components and top navigation
- Replace detail modals with dedicated pages (users, broadcasts, email templates)
- Add email channel support for broadcasts
- Remove pull-to-refresh, improve drag-and-drop on touch devices
- Fix Telegram Mini App: fullscreen, back button, scroll restoration
- Unify admin pages color scheme to design system
- Mobile-first improvements: horizontal tabs for settings, better touch targets

src/components/primitives/Switch/Switch.tsx

@@ -0,0 +1,73 @@
+import * as SwitchPrimitive from '@radix-ui/react-switch';
+import { motion } from 'framer-motion';
+import { forwardRef, type ComponentPropsWithoutRef } from 'react';
+import { cn } from '@/lib/utils';
+import { usePlatform } from '@/platform';
+import { springTransition } from '../../motion/transitions';
+
+export interface SwitchProps extends Omit<
+  ComponentPropsWithoutRef<typeof SwitchPrimitive.Root>,
+  'onChange'
+> {
+  label?: string;
+  description?: string;
+  onChange?: (checked: boolean) => void;
+  haptic?: boolean;
+}
+
+export const Switch = forwardRef<HTMLButtonElement, SwitchProps>(
+  ({ className, label, description, onChange, onCheckedChange, haptic = true, ...props }, ref) => {
+    const { haptic: platformHaptic } = usePlatform();
+
+    const handleCheckedChange = (checked: boolean) => {
+      if (haptic) {
+        platformHaptic.impact('light');
+      }
+      onCheckedChange?.(checked);
+      onChange?.(checked);
+    };
+
+    const switchElement = (
+      <SwitchPrimitive.Root
+        ref={ref}
+        className={cn(
+          'peer inline-flex h-6 w-11 shrink-0 cursor-pointer items-center rounded-full',
+          'border-2 border-transparent transition-colors duration-200',
+          'focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-accent-500/50 focus-visible:ring-offset-2 focus-visible:ring-offset-dark-950',
+          'disabled:cursor-not-allowed disabled:opacity-50',
+          'data-[state=checked]:bg-accent-500 data-[state=unchecked]:bg-dark-700',
+          className,
+        )}
+        onCheckedChange={handleCheckedChange}
+        {...props}
+      >
+        <SwitchPrimitive.Thumb asChild>
+          <motion.span
+            className={cn(
+              'pointer-events-none block h-5 w-5 rounded-full bg-white shadow-lg ring-0',
+              'data-[state=checked]:translate-x-5 data-[state=unchecked]:translate-x-0',
+            )}
+            layout
+            transition={springTransition}
+          />
+        </SwitchPrimitive.Thumb>
+      </SwitchPrimitive.Root>
+    );
+
+    if (!label) {
+      return switchElement;
+    }
+
+    return (
+      <label className="flex cursor-pointer items-center justify-between gap-4">
+        <div className="min-w-0 flex-1">
+          <span className="block text-sm font-medium text-dark-100">{label}</span>
+          {description && <span className="mt-0.5 block text-sm text-dark-400">{description}</span>}
+        </div>
+        {switchElement}
+      </label>
+    );
+  },
+);
+
+Switch.displayName = 'Switch';