ios: right-align user bubbles on iPad

ios/Packages/Sybil/Sources/Sybil/SybilChatTranscriptView.swift

@@ -25,6 +25,7 @@ struct SybilChatTranscriptView: View {
 
                     ForEach(messages) { message in
                         MessageBubble(message: message, isSending: isSending)
+                            .frame(maxWidth: .infinity)
                             .id(message.id)
                     }
 
@@ -86,10 +87,8 @@ private struct MessageBubble: View {
     }
 
     var body: some View {
-        HStack(alignment: .top) {
-            if isUser {
-                Spacer(minLength: 44)
-            }
+        HStack(alignment: .top, spacing: 0) {
+            leadingSpacer
 
             if let toolCallMetadata {
                 ToolCallActivityChip(
@@ -136,12 +135,24 @@ private struct MessageBubble: View {
                 .frame(maxWidth: isUser ? 420 : nil, alignment: isUser ? .trailing : .leading)
             }
 
+            trailingSpacer
+        }
+        .frame(maxWidth: .infinity, alignment: isUser ? .trailing : .leading)
+    }
+
+    @ViewBuilder
+    private var leadingSpacer: some View {
+        if isUser {
+            Spacer(minLength: 44)
+        }
+    }
+
+    @ViewBuilder
+    private var trailingSpacer: some View {
         if !isUser {
             Spacer(minLength: 0)
         }
     }
-        .frame(maxWidth: .infinity, alignment: isUser ? .trailing : .leading)
-    }
 }
 
 private struct ToolCallActivityChip: View {