feat: add clsx and tailwind-merge dependencies, enhance Kanban components

- Added `clsx` and `tailwind-merge` to `package.json` and `package-lock.json` for improved class management and utility merging.
- Updated `Column` and `TaskCard` components to utilize new UI components (`Card`, `Badge`) for a more cohesive design.
- Refactored styles in `Header` and Kanban components to align with the new design system.
- Marked several tasks as completed in `TODO.md` reflecting progress on UI enhancements.

components/ui/Input.tsx

@@ -0,0 +1,44 @@
+import { InputHTMLAttributes, forwardRef } from 'react';
+import { cn } from '@/lib/utils';
+
+interface InputProps extends InputHTMLAttributes<HTMLInputElement> {
+  label?: string;
+  error?: string;
+}
+
+const Input = forwardRef<HTMLInputElement, InputProps>(
+  ({ className, label, error, ...props }, ref) => {
+    return (
+      <div className="space-y-2">
+        {label && (
+          <label className="block text-sm font-mono font-medium text-slate-300 uppercase tracking-wider">
+            {label}
+          </label>
+        )}
+        <input
+          className={cn(
+            'w-full px-3 py-2 bg-slate-800/50 border border-slate-700/50 rounded-lg',
+            'text-slate-100 font-mono text-sm placeholder-slate-500',
+            'focus:outline-none focus:ring-2 focus:ring-cyan-500/50 focus:border-cyan-500/50',
+            'hover:border-slate-600/50 transition-all duration-200',
+            'backdrop-blur-sm',
+            error && 'border-red-500/50 focus:ring-red-500/50 focus:border-red-500/50',
+            className
+          )}
+          ref={ref}
+          {...props}
+        />
+        {error && (
+          <p className="text-xs font-mono text-red-400 flex items-center gap-1">
+            <span className="text-red-500">⚠</span>
+            {error}
+          </p>
+        )}
+      </div>
+    );
+  }
+);
+
+Input.displayName = 'Input';
+
+export { Input };