Normalize Block Library JSX Test Filenames

[ciampo]

What?

See #80855.

TL;DR: Prepares Block Library for native Vitest transforms through two mechanical change classes: ten .js to .jsx test renames and executable-baseline identity mappings.

This stacked draft contains only filename and manifest changes and is based on #80970.

Why?

Ten Block Library tests contain JSX while using .js. Renaming them before the runner migration avoids making .js a permanent JSX loader contract in the Vitest execution path.

How?

• Renames the ten parser-confirmed Block Library test files with byte-identical contents.
• Preserves their executable baseline identities in the migration manifest.
• Reduces the JSX-in-.js baseline from 1,187 to 1,177 files.

Runner ownership, assertions, and snapshots do not change.

Testing Instructions

• npm run test:unit -- --runInBand packages/block-library
  • 55 files, 669 tests, and 1 snapshot pass before and after the renames.
• npm run test:unit:routing
  • 249 Jest files and 754 Vitest files remain owned exactly once; 75 baseline paths are tracked as renames.
• npm run test:unit:conventions
• npm exec lint-staged -- --no-stash

Use of AI Tools

This parser-backed rename inventory, manifest update, and verification were prepared with Codex. Every rename was reviewed as 100% content-preserving before opening this draft.

[github-actions]

Size Change: 0 B

Total Size: 7.76 MB

_{compressed-size-action}

[github-actions]

Flaky tests detected in 397c1a4.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/30549104282
📝 Reported issues:

• [Flaky Test] should cut and paste individual blocks with collapsed selection #80248 in /test/e2e/specs/editor/various/copy-cut-paste.spec.js