feat: improve test & bundler (#14434)

#### PR Dependency Tree


* **PR #14434** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Introduced rspack bundler as an alternative to webpack for optimized
builds.

* **Tests & Quality**
* Added comprehensive editor semantic tests covering markdown, hotkeys,
and slash-menu operations.
* Expanded CI cross-browser testing to Chromium, Firefox, and WebKit;
improved shape-rendering tests to account for zoom.

* **Bug Fixes**
  * Corrected CSS overlay styling for development servers.
  * Fixed TypeScript typings for build tooling.

* **Other**
  * Document duplication now produces consistent "(n)" suffixes.
  * French i18n completeness increased to 100%.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/apps/electron-renderer/src/app/global.css

@@ -6,7 +6,8 @@ textarea
   -webkit-app-region: no-drag;
 }
 
-#webpack-dev-server-client-overlay {
+#webpack-dev-server-client-overlay,
+#rspack-dev-server-client-overlay {
   -webkit-app-region: no-drag;
 }