feat: make relay status indicator smaller and hide on scroll

- Reduce overall size of indicator on desktop (smaller padding, font sizes)
- On mobile, match size with sidebar toggle buttons (var(--min-touch-target))
- Auto-collapse on mobile (collapsed by default, tap to expand)
- Hide when scrolling down on mobile, show when scrolling up
- Match behavior of other mobile UI controls for consistency

src/components/ThreePaneLayout.tsx

@@ -366,7 +366,10 @@ const ThreePaneLayout: React.FC<ThreePaneLayoutProps> = (props) => {
           highlightColor={props.settings.highlightColorMine || '#ffff00'}
         />
       )}
-      <RelayStatusIndicator relayPool={props.relayPool} />
+      <RelayStatusIndicator 
+        relayPool={props.relayPool}
+        showOnMobile={showMobileButtons}
+      />
       {props.toastMessage && (
         <Toast
           message={props.toastMessage}