fix(dashboard): anchor Refresh and Settings buttons to bottom

Fixed panel layout to properly position bottom buttons:

**Changes:**
1. #rpg-panel-content: Changed overflow-y from 'hidden' to 'auto'
   - Allows panel to scroll when needed

2. .rpg-dashboard-container: Added flex properties
   - flex: 1 - Grows to fill available space
   - overflow-y: auto - Scrolls internally when content overflows
   - min-height: 0 - Allows shrinking in flex context

**Result:**
Creates proper flex layout where:
- Dice display stays at top (fixed size)
- Dashboard container fills middle and scrolls (flex: 1)
- Toggle/Refresh/Settings buttons anchor at bottom (fixed size)

Fixes issue where buttons appeared in middle of panel instead of bottom.

style.css

@@ -380,7 +380,7 @@ body:has(.rpg-panel.rpg-position-left) #sheld {
     display: flex;
     flex-direction: column;
     gap: 0.375em;
-    overflow-y: hidden;
+    overflow-y: auto;
     overflow-x: hidden;
     min-height: 0;
 }
@@ -1051,6 +1051,9 @@ body:has(.rpg-panel.rpg-position-left) #sheld {
     flex-direction: column;
     gap: 0.75rem;
     width: 100%;
+    flex: 1;
+    overflow-y: auto;
+    min-height: 0;
 }
 
 .rpg-dashboard-header {