fix(mobile): respect topbar height and enable proper scrolling

- Changed top: auto to top: var(--topBarBlockSize) to prevent panel from covering SillyTavern topbar
- Removed fixed height: 70vh/80vh properties that prevented proper sizing
- Panel height now determined by top/bottom constraints for natural fit
- Changed overflow-y: auto to overflow-y: scroll for reliable scrolling
- Added -webkit-overflow-scrolling: touch for iOS smooth scrolling
- Fixes panel covering entire screen, content squishing, and scroll issues

style.css

@@ -2916,28 +2916,20 @@ body:has(.rpg-panel.rpg-position-left) #sheld {
     .rpg-panel.rpg-position-left,
     .rpg-panel.rpg-position-top {
         position: fixed;
-        top: auto;
+        top: var(--topBarBlockSize);
         bottom: 0;
         left: 0;
         right: 0;
         width: 100%;
         max-width: 100%;
-        height: 70vh;
-        max-height: 70vh;
         border-radius: 20px 20px 0 0;
-        overflow-y: auto;
+        overflow-y: scroll;
+        -webkit-overflow-scrolling: touch;
     }
 }
 
-/* Extra small screens - more height */
+/* Extra small screens - adjust FAB position */
 @media (max-width: 480px) {
-    .rpg-panel.rpg-position-right,
-    .rpg-panel.rpg-position-left,
-    .rpg-panel.rpg-position-top {
-        height: 80vh;
-        max-height: 80vh;
-    }
-    
     .rpg-mobile-toggle {
         bottom: 70px;
         right: 15px;