fix(studio): restore pulsing sidebar connection dot when connected

The collapsed connection dot was a static Container after the sidebar
refactor; route it through the shared ChainStatusDot with pulsing tied
to the connected state — a living live-signal, steady when down or
unknown.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/main.dart

@@ -1183,21 +1183,10 @@ class _CollapsedConnectionDot extends StatelessWidget {
         : connected == false
         ? theme.colorScheme.error
         : ChainColors.warning;
-    return Container(
-      width: 10,
-      height: 10,
-      decoration: BoxDecoration(
-        color: color,
-        shape: BoxShape.circle,
-        boxShadow: [
-          BoxShadow(
-            color: color.withValues(alpha: 0.35),
-            blurRadius: 4,
-            spreadRadius: 0.5,
-          ),
-        ],
-      ),
-    );
+    // Pulse only while connected — a living "this is live" signal,
+    // steady when down/unknown. Restores the pulse lost in the
+    // sidebar refactor; reuses the shared ChainStatusDot.
+    return ChainStatusDot(color: color, pulsing: connected == true, size: 10);
   }
 }