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 -->

tools/cli/src/bundler.ts

@@ -0,0 +1,27 @@
+export const SUPPORTED_BUNDLERS = ['webpack', 'rspack'] as const;
+
+export type Bundler = (typeof SUPPORTED_BUNDLERS)[number];
+
+export const DEFAULT_BUNDLER: Bundler = 'rspack';
+
+function isBundler(value: string): value is Bundler {
+  return SUPPORTED_BUNDLERS.includes(value as Bundler);
+}
+
+export function normalizeBundler(input: string | undefined | null): Bundler {
+  const value = input?.trim().toLowerCase();
+  if (!value) {
+    return DEFAULT_BUNDLER;
+  }
+  if (isBundler(value)) {
+    return value;
+  }
+
+  throw new Error(
+    `Unsupported AFFINE_BUNDLER: "${input}". Expected one of: ${SUPPORTED_BUNDLERS.join(', ')}.`
+  );
+}
+
+export function getBundler(env: NodeJS.ProcessEnv = process.env): Bundler {
+  return normalizeBundler(env.AFFINE_BUNDLER);
+}