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/icons/android/mipmap-anydpi-v26/ic_launcher.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+  <foreground android:drawable="@mipmap/ic_launcher_foreground"/>
+  <background android:drawable="@color/ic_launcher_background"/>
+</adaptive-icon>

src-tauri/icons/android/values/ic_launcher_background.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+  <color name="ic_launcher_background">#fff</color>
+</resources>