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/i18n/src/i18n-completenesses.json

@@ -9,7 +9,7 @@
   "es-CL": 98,
   "es": 96,
   "fa": 96,
-  "fr": 98,
+  "fr": 100,
   "hi": 1,
   "it-IT": 98,
   "it": 1,

packages/frontend/i18n/src/resources/fr.json

@@ -2311,4 +2311,3 @@
   "error.RESPONSE_TOO_LARGE_ERROR": "Réponse trop volumineuse ({{receivedBytes}} octets), la limite est de {{limitBytes}} octets",
   "error.SSRF_BLOCKED_ERROR": "URL invalide"
 }
-