feat: Story 9 - Remove scroll bars for cleaner UI

Implemented Story 9: Hidden Scroll Bars
- Added CSS to hide scroll bars globally while maintaining functionality
- Used scrollbar-width: none for Firefox
- Used ::-webkit-scrollbar { display: none; } for Chrome/Safari/Edge
- Set overflow-x: hidden to prevent unwanted horizontal scrolling
- Maintained full scroll functionality (mouse wheel, trackpad, keyboard)

Updated Specs
- Added Scroll Bar Styling section to UI_UX.md
- Documented cross-browser compatibility requirements
- Specified areas affected and implementation approach

Bug Fixes
- Fixed biome linting issues in App.tsx (import organization, button type)
- Applied biome formatter for consistent code style

src/App.css

@@ -158,3 +158,20 @@ details summary span:first-child {
     background: transparent;
     padding: 0;
 }
+
+/* Hide scroll bars globally while maintaining scroll functionality */
+/* Firefox */
+* {
+    scrollbar-width: none;
+}
+
+/* Chrome, Safari, Edge */
+*::-webkit-scrollbar {
+    display: none;
+}
+
+/* Ensure scroll functionality is maintained */
+body,
+html {
+    overflow-x: hidden;
+}