Feat: Added a Statistics node #2018

[mzabuawala]

Fixes - #2018

Summary by CodeRabbit

• New Features

  • Added Extended Statistics: schema browser node and dialog to create/view/update/delete column- or expression-based statistics; version-aware SQL generation (PG14/16/17), dependency graph and schema-diff support, context menus, client-side validation, and editor integration.

• Tests

  • Added integration/regression tests and fixtures covering create/get/update/delete, list/delete-multiple, validation and error cases.

• Documentation

  • New statistics dialog docs and release notes entry.