feat: replace clsx with cn util

src/shared/ui/Input/Input.svelte

@@ -3,8 +3,8 @@
     design-system input. Zero border-radius, Space Grotesk, precise states.
 -->
 <script lang="ts">
+import { cn } from '$shared/lib';
 import XIcon from '@lucide/svelte/icons/x';
-import clsx from 'clsx';
 import type { Snippet } from 'svelte';
 import { cubicOut } from 'svelte/easing';
 import type { HTMLInputAttributes } from 'svelte/elements';
@@ -90,7 +90,7 @@ const hasRightSlot = $derived(!!rightIcon || showClearButton);
 const cfg = $derived(inputSizeConfig[size]);
 const styles = $derived(inputVariantConfig[variant]);
 
-const inputClasses = $derived(clsx(
+const inputClasses = $derived(cn(
     'font-primary rounded-none outline-none transition-all duration-200',
     'text-neutral-900 dark:text-neutral-100',
     'placeholder:text-neutral-400 dark:placeholder:text-neutral-600',
@@ -107,8 +107,8 @@ const inputClasses = $derived(clsx(
 ));
 </script>
 
-<div class={clsx('flex flex-col gap-1', fullWidth && 'w-full')}>
-    <div class={clsx('relative group', fullWidth && 'w-full')}>
+<div class={cn('flex flex-col gap-1', fullWidth && 'w-full')}>
+    <div class={cn('relative group', fullWidth && 'w-full')}>
         <!-- Left icon slot -->
         {#if leftIcon}
             <div class="absolute left-3 top-1/2 -translate-y-1/2 text-neutral-400 dark:text-neutral-600 pointer-events-none z-10 flex items-center">
@@ -147,7 +147,7 @@ const inputClasses = $derived(clsx(
     <!-- Helper / error text -->
     {#if helperText}
         <span
-            class={clsx(
+            class={cn(
                 'text-2xs font-mono tracking-wide px-1',
                 error ? 'text-brand ' : 'text-secondary',
             )}