Fix CloudFormation validation error logging

- Use Rich console.print with markup=False to prevent markup parsing errors
- Display readable error message using str(e) instead of JSON formatting
- Fixes MarkupError when CloudFormation errors contain square brackets
- Remove unnecessary f-string prefix and apply code formatting

Author: Taniya Mathur

publish.py

@@ -1368,7 +1368,10 @@ def build_main_template(self, webui_zipfile, components_needing_rebuild):
         except ClientError as e:
             # Delete checksum on template validation failure
             self._delete_checksum_file(".checksum")
-            self.console.print(f"[red]Template validation failed: {e}[/red]")
+            self.console.print(
+                "[red]❌ CloudFormation template validation failed[/red]"
+            )
+            self.console.print(str(e), style="red", markup=False)
             sys.exit(1)
         except Exception as e:
             # Delete checksum on any failure to force rebuild next time