feat(chat): add trailing comma rules

analysis_options.yaml

@@ -27,7 +27,9 @@ dart_code_metrics:
 #   maximum-nesting-level: 5
 # metrics-exclude:
 #   - test/**
-# rules:
+linter:
+  rules:
+    require_trailing_commas: true
 #   - newline-before-return
 #   - no-boolean-literal-compare
 #   - no-empty-block