feat: show tool status notifications in chat during generation

Parse SSE `status` events alongside `chunk` events and display the
status text next to the spinner while the assistant is generating.
Previously the Android app discarded all non-chunk SSE events.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/widgets/chat_message_bubble.dart

@@ -7,7 +7,12 @@ import '../data/models/message.dart';
 
 class ChatMessageBubble extends StatelessWidget {
   final Message message;
-  const ChatMessageBubble({super.key, required this.message});
+  final String streamingStatus;
+  const ChatMessageBubble({
+    super.key,
+    required this.message,
+    this.streamingStatus = '',
+  });
 
   @override
   Widget build(BuildContext context) {
@@ -53,13 +58,31 @@ class ChatMessageBubble extends StatelessWidget {
         child: Padding(
           padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
           child: isGenerating && message.content.isEmpty
-              ? SizedBox(
-                  width: 20,
-                  height: 20,
-                  child: CircularProgressIndicator(
-                    strokeWidth: 2,
-                    color: scheme.onSurfaceVariant,
-                  ),
+              ? Row(
+                  mainAxisSize: MainAxisSize.min,
+                  children: [
+                    SizedBox(
+                      width: 16,
+                      height: 16,
+                      child: CircularProgressIndicator(
+                        strokeWidth: 2,
+                        color: scheme.onSurfaceVariant,
+                      ),
+                    ),
+                    if (streamingStatus.isNotEmpty) ...[
+                      const SizedBox(width: 8),
+                      Flexible(
+                        child: Text(
+                          streamingStatus,
+                          style: TextStyle(
+                            fontSize: 12,
+                            color: scheme.onSurfaceVariant,
+                            fontStyle: FontStyle.italic,
+                          ),
+                        ),
+                      ),
+                    ],
+                  ],
                 )
               : MarkdownBody(
                   data: message.content.isEmpty ? '…' : message.content,