feat(logging): add logging to ChatBloc

apps/lib/features/chat/presentation/bloc/chat_bloc_send.dart

@@ -4,6 +4,14 @@ part of 'chat_bloc.dart';
 
 extension _ChatBlocSend on ChatBloc {
   Future<void> _sendMessage(String content, {List<XFile>? images}) async {
+    _logger.info(
+      message: 'Sending chat message',
+      extra: {
+        'message_length': content.length,
+        'attachments_count': images?.length ?? 0,
+      },
+    );
+
     final epoch = _sessionEpoch;
     final assistantBaselineAtSend = chatBlocLatestAssistantTimestamp(
       state.items,
@@ -57,11 +65,21 @@ extension _ChatBlocSend on ChatBloc {
       if (epoch != _sessionEpoch) {
         return;
       }
+      _logger.info(
+        message: 'Chat message sent successfully',
+        extra: {'message_id': messageId},
+      );
       _syncUploadedAttachments(
         messageId: messageId,
         uploadedAttachments: sendResult.uploadedAttachments,
       );
-    } catch (error) {
+    } catch (error, stackTrace) {
+      _logger.error(
+        message: 'Failed to send chat message',
+        error: error,
+        stackTrace: stackTrace,
+        extra: {'message': content},
+      );
       if (epoch != _sessionEpoch) {
         return;
       }