Port jsonwebtoken ESM test utility module

Bun corpus slice

• Position 4030: js/third_party/jsonwebtoken/set_headers.test.js (already green, 2/2)
• Position 4031: js/third_party/jsonwebtoken/test-utils.js

Gap

The helper is discovered by the corpus scanner as a test-shaped JavaScript file, but it is an ESM utility module with named and default exports rather than a standalone test. Home currently rewrites its import but leaves the export declarations for the script evaluator, producing SyntaxError: Unexpected keyword 'export'.

Acceptance criteria

• evaluate the real helper implementation and register its named/default utility surface for jsonwebtoken tests
• treat successful standalone helper evaluation as an intentional empty fixture, not an unsupported file
• retain synchronous/asynchronous JWT result and structured-error parity
• add the helper to the permanent JWT/utility mini-suite
• focused positions 4030–4031 pass with zero failures or unsupported files

Implemented and pushed in c1922c6 (feat(third-party): port JWT test utilities).

What landed:

• Bun's real test-utils.js helper now evaluates after ESM-to-bootstrap rewriting
• named helpers and the default helper object are registered together under ./test-utils
• the upstream helper's synchronous/asynchronous token and structured-error comparison behavior is preserved
• its standalone execution is explicitly recognized as an intentional helper fixture with no registered tests
• the file is now part of the permanent third-party JWT/utility mini-suite

Verification:

• position 4031: 0 failed, 0 unsupported, 1 intentional allowed-empty fixture
• sequential positions 4030–4032: 4 passed, 0 failed/todo/unsupported, 1 allowed-empty fixture
• always-on JWT/utility mini-suite: passed
• gRPC stack diagnostics and SQL adapter contracts: passed

This advances the contiguous full-corpus boundary through position 4032: 374 files, 3,389 passed, 225 todo, 0 failed, 0 unsupported (172 allowlisted empty files).