docs: Add Query Estimator to community extensions registry (#36814)

docs/developer_portal/extensions/registry.md

@@ -35,6 +35,7 @@ This page serves as a registry of community-created Superset extensions. These e
 | [SQL Lab Export to Google Sheets](https://github.com/michael-s-molina/superset-extensions/tree/main/sqllab_gsheets) | A Superset extension that allows users to export SQL Lab query results directly to Google Sheets.                                                                                                                                                   | Michael S. Molina  | <a href="/img/extensions/gsheets-export.png" target="_blank"><img src="/img/extensions/gsheets-export.png" alt="SQL Lab Export to Google Sheets" width="120" /></a> |
 | [SQL Lab Export to Parquet](https://github.com/rusackas/superset-extensions/tree/main/sqllab_parquet)               | Export SQL Lab query results directly to Apache Parquet format with Snappy compression.                                                                                                                                                             | Evan Rusackas      | <a href="/img/extensions/parquet-export.png" target="_blank"><img src="/img/extensions/parquet-export.png" alt="SQL Lab Export to Parquet" width="120" /></a>       |
 | [SQL Lab Query Comparison](https://github.com/michael-s-molina/superset-extensions/tree/main/query_comparison)      | A SQL Lab extension that enables side-by-side comparison of query results across different tabs, with GitHub-style diff visualization showing added/removed rows and columns.                                                                       | Michael S. Molina  | <a href="/img/extensions/query-comparison.png" target="_blank"><img src="/img/extensions/query-comparison.png" alt="Query Comparison" width="120" /></a>            |
+| [SQL Lab Query Estimator](https://github.com/michael-s-molina/superset-extensions/tree/main/query_estimator)        | A SQL Lab panel that analyzes query execution plans to estimate resource impact, detect performance issues like Cartesian products and high-cost operations, and visualize the query plan tree.                                                     | Michael S. Molina  | <a href="/img/extensions/query-estimator.png" target="_blank"><img src="/img/extensions/query-estimator.png" alt="Query Estimator" width="120" /></a>               |
 
 ## How to Add Your Extension