feat: responsive mobile UI across all pages

Global:
- Viewport meta already present; added -webkit-text-size-adjust: 100%
- Container padding reduces to 12px on mobile (was 24px)
- Smaller heading sizes (h1: 1.5rem, h2: 1.25rem)
- Buttons get min-height 40px for touch targets
- Inputs forced to 16px font-size to prevent iOS zoom
- Thinner scrollbar on mobile

Header:
- Logo text shrinks to 1rem on mobile, icon to 28px
- Header padding reduces to 12px

Library:
- Toolbar stacks vertically on mobile, full-width inputs
- Grid forced to 2 columns on narrow screens (480px), reduced gap

GameCard:
- Smaller info text, padding, badge on 480px screens

GameDetail:
- Cover section capped at 200px width on mobile
- Media thumbnails shrink to 160x90
- Scrape header stacks vertically with full-width buttons
- Edit rows stack vertically on mobile

Play:
- DOS container caps at 50vh on mobile, smaller border-radius
- Overlay text/icon sizes reduced, more compact layout

frontend/src/lib/GameCard.svelte

@@ -87,6 +87,12 @@
     overflow: hidden;
     text-overflow: ellipsis;
   }
+  @media (max-width: 480px) {
+    .info { padding: 8px; }
+    .info h3 { font-size: 0.8rem; }
+    .year, .genre { font-size: 0.7rem; }
+    .badge { font-size: 0.6rem; padding: 1px 6px; top: 4px; right: 4px; }
+  }
   .year, .genre {
     font-size: 0.8rem;
     color: var(--text-dim);