Add polished UX: tabs, kinetic scroll, animations, search, typography

- Tabbed interface with duplicate detection, overflow scroll arrows,
  mouse wheel support, and animated enter/exit transitions
- Kinetic scrolling on right-mouse drag with iOS-style rubber band
  overscroll and damped spring snapback (content area and sidebar)
- Framer Motion animations on sidebar, context menu, drop zone,
  focus mode, tabs, and all modals
- Full-text search with real-time DOM highlighting and match navigation
- Custom OverlayScrollbars replacing native scrollbars
- Tauri native drag-and-drop replacing broken browser drag events
- UI scale control (View menu spinner) persisted to localStorage
- Content zoom (Ctrl+Scroll) and width adjustment (Shift+Scroll)
- Right-click context menu with copy, zoom-adjusted positioning,
  and boundary clamping
- Text selection preserved on right-click via visual overlay
- Focus mode hides title/menu bars with animated transitions
- Premium editorial typography: progressive heading color cascade,
  gradient-fade horizontal rules, accent-colored list markers,
  subtle persistent link underlines, refined blockquotes and code blocks
- Sidebar table of contents with "No headings" empty state
- Markdown breaks and typographer enabled
- New app icons and updated README with full feature documentation

src-tauri/src/main.rs

@@ -2,5 +2,5 @@
 #![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]
 
 fn main() {
-    darkmark_lib::run()
+    vesper_lib::run()
 }