feat: hide zoom control on mobile devices

- Hide zoom control on mobile viewports (≤768px) via CSS
- Skip loading saved zoom on mobile, always use 100%
- Add resize handler to reset zoom when switching to mobile view
- Clean up unnecessary mobile-specific zoom styles
- Prevents confusion on touch devices where zoom is less useful

static/css/main.css

@@ -3642,30 +3642,7 @@ html {
 /* Mobile Responsive - Smaller on mobile */
 @media (max-width: 768px) {
     .zoom-control {
-        bottom: 50px;
-        padding: 0.4rem 0.8rem;
-        gap: 0.4rem;
-    }
-
-    .zoom-slider {
-        width: 140px;
-    }
-
-    .zoom-value {
-        font-size: 0.7rem;
-        min-width: 25px;
-    }
-
-    .zoom-value-current {
-        font-size: 0.8rem;
-        min-width: 30px;
-    }
-
-    .zoom-reset-btn {
-        min-width: 38px;
-        min-height: 38px;
-        font-size: 0.7rem;
-        padding: 0.4rem;
+        display: none; /* Hide zoom control on mobile - not useful on small screens */
     }
 }