fix: expand collapsed notch for session state dots (farouqaldori#37)

* fix: expand collapsed notch for session state dots

Add expansion width calculation for the multiple active sessions case.
When only hasMultipleActiveSessions is true (without processing,
permission, or waitingForInput), the notch now properly expands to
accommodate the crab icon and session state dots.

Previously, showClosedActivity was true but expansionWidth returned 0,
causing dots to be crammed within the fixed notch width.

* fix: add right-side spacer for symmetric notch expansion with session dots

The expansionWidth calculation and closedContentWidth property weren't
actually driving layout - expansion worked via HStack content sizing.
When only hasMultipleActiveSessions was true (no processing/pending/
waitingForInput), the right side had no content, causing asymmetric
expansion unlike other activity states.

Changes:
- Add empty Color.clear spacer on right side when showing session dots
- Update expansionWidth formula to match symmetric layout (2 * sideWidth)

Author: engels74

ClaudeIsland/UI/Views/NotchView.swift

@@ -203,6 +203,12 @@ struct NotchView: View {
             return 2 * max(0, self.closedNotchSize.height - 12) + 20
         }
 
+        // Expand for multiple active sessions to accommodate session state dots
+        // Uses symmetric expansion (sideWidth on both left and right) like processing
+        if self.hasMultipleActiveSessions {
+            return 2 * max(0, self.closedNotchSize.height - 12) + 20
+        }
+
         return 0
     }
 
@@ -327,7 +333,8 @@ struct NotchView: View {
                 }
             }
 
-            // Right side - spinner when processing/pending, checkmark when waiting for input
+            // Right side - spinner when processing/pending, checkmark when waiting for input,
+            // or empty spacer for symmetric expansion with session dots
             if self.showClosedActivity {
                 if self.isProcessing || self.hasPendingPermission {
                     ProcessingSpinner()
@@ -340,6 +347,12 @@ struct NotchView: View {
                         .matchedGeometryEffect(id: "spinner", in: self.activityNamespace, isSource: self.showClosedActivity)
                         .frame(width: self.viewModel.status == .opened ? 20 : self.sideWidth)
                         .padding(.trailing, self.viewModel.status == .opened ? 0 : 4)
+                } else if self.hasMultipleActiveSessions && self.viewModel.status != .opened {
+                    // Empty spacer maintains symmetric expansion when showing session dots
+                    // (matches sideWidth used by spinner/checkmark in other activity states)
+                    Color.clear
+                        .frame(width: self.sideWidth)
+                        .padding(.trailing, 4)
                 }
             }
         }