feat: implement responsive design enhancements

- Add touch-optimized tap targets (44x44px minimum for iOS)
- Enhance mobile responsiveness across all components
- Improve button sizing and spacing for touch interactions
- Add responsive text sizing and layout adjustments
- Implement mobile-first modal behavior (bottom sheet on mobile)
- Enhance form controls with better touch targets
- Add active states for better touch feedback
- Improve grid layouts for various screen sizes
- Add smooth scrolling and better focus states
- Optimize FilterPanel for mobile with grid layouts
- Enhance all interactive elements with tap-target classes

Requirements: 7.1, 7.2

components/NewListButton.tsx

@@ -12,10 +12,11 @@ export default function NewListButton() {
     <>
       <button 
         onClick={() => setIsModalOpen(true)}
-        className="bg-blue-500 hover:bg-blue-600 text-white px-4 py-2 rounded-lg flex items-center gap-2 transition-colors"
+        className="bg-blue-500 hover:bg-blue-600 active:bg-blue-700 text-white px-4 sm:px-6 py-3 rounded-lg flex items-center gap-2 transition-colors tap-target shadow-sm hover:shadow-md text-sm sm:text-base font-medium"
       >
-        <PlusIcon size={20} />
-        New List
+        <PlusIcon size={20} className="flex-shrink-0" />
+        <span className="hidden xs:inline sm:inline">New List</span>
+        <span className="xs:hidden sm:hidden">New</span>
       </button>
 
       <Modal