feat: tooltips, two-column timer, font selector, tray behavior, icons, readme

- Custom tooltip directive (WCAG AAA) on every button in the app
- Two-column timer layout with sticky hero and recent entries sidebar
- Timer font selector with 16 monospace Google Fonts and live preview
- UI font selector with 15+ Google Fonts
- Close-to-tray and minimize-to-tray settings
- New app icons (no-glow variants), platform icon set
- Mini timer pop-out window
- Favorites strip with drag-reorder and inline actions
- Comprehensive README with feature documentation
- Remove tracked files that belong in gitignore

src-tauri/src/main.rs

@@ -4,5 +4,5 @@
 )]
 
 fn main() {
-    local_time_tracker_lib::run();
+    zeroclock_lib::run();
 }