fix(ui): improve issues page toolbar and rows for mobile

- Make Filter/Sort/Group buttons icon-only on small screens (< 640px)
- Make "New Issue" button icon-only on small screens
- Show filter count badge on mobile instead of full text
- Reduce gaps between toolbar items on mobile
- Hide date column and "Live" text on small screens for issue rows
- Add touch-action: manipulation to prevent double-tap zoom on mobile

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ui/src/index.css

@@ -120,6 +120,16 @@
   body {
     @apply bg-background text-foreground;
   }
+  /* Prevent double-tap-to-zoom on interactive elements for mobile */
+  a,
+  button,
+  [role="button"],
+  input,
+  select,
+  textarea,
+  label {
+    touch-action: manipulation;
+  }
 }
 
 /* Dark mode scrollbars */