feat(shared/lib): add cn utility (clsx + tailwind-merge)

src/shared/lib/cn.test.ts

@@ -0,0 +1,16 @@
+import { describe, expect, it } from 'vitest';
+import { cn } from './cn';
+
+describe('cn', () => {
+    it('merges class strings', () => {
+        expect(cn('foo', 'bar')).toBe('foo bar');
+    });
+
+    it('deduplicates conflicting Tailwind classes (last wins)', () => {
+        expect(cn('p-4', 'p-8')).toBe('p-8');
+    });
+
+    it('ignores falsy values', () => {
+        expect(cn('foo', false, undefined, null, 'bar')).toBe('foo bar');
+    });
+});

src/shared/lib/cn.ts

@@ -0,0 +1,7 @@
+import { clsx, type ClassValue } from 'clsx';
+import { twMerge } from 'tailwind-merge';
+
+/** Merge Tailwind classes without conflicts. Later classes win on collision. */
+export function cn(...inputs: ClassValue[]): string {
+    return twMerge(clsx(inputs));
+}

src/shared/lib/index.ts

@@ -1 +1,2 @@
 export * from './api';
+export { cn } from './cn';