Tests: Recognize Chromium browser project in routing validation

[ciampo]

Based on #82567. Required by the browser tests for #66806.

What?

Allow the routing validator to recognize Vitest's configured Chromium browser instance.

Why?

Adding a browser test makes npm run test:unit:routing fail with Unexpected Vitest project browser (chromium), even though the test belongs to the configured browser project.

How?

Map that exact instance name to browser. Keep the existing checks for unknown projects, missing files, and duplicate test ownership.

Testing Instructions

1. Add a temporary test/unit/scripts/test/routing.browser.test.js containing import { test } from 'vitest'; test( 'browser routing', () => {} );.
2. Run npm run test:unit:routing. It should recognize the browser test and validate one runner per test file.
3. Remove the temporary test and run the command again.

Verification

Reproduced the failure with the component migration's browser tests. With this change, routing validates all 1,106 test files: 38 Jest and 1,068 Vitest. JavaScript lint passes.

Use of AI Tools

Authored and verified with Codex.

[github-actions]

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📦 Bundle size

Size Change: 0 B

Total Size: 8 MB

_{c2b5092 Run}

[ciampo]

Closing as superseded by #82574