Activate mock.module missing-package resolution regression

Tracks a focused Bun parity slice under #66.

Scope:

• activate upstream js/bun/test/mock/mock-module-resolve-log.test.ts
• verify mock.module() can register a factory for a package absent from disk/registry
• ensure lowered dynamic import() resolves the mock before package lookup
• cover the stale package-manager resolver-log crash regression
• add a dedicated native corpus regression and verify the mock directory

Implemented and pushed in 7036b9d4486b385debc8b095883bada74a8fd464 (feat(test): activate mock module resolver regression).

Verification:

• exact upstream file: 1 passed, 0 failed, 0 unsupported, 0 todo
• js/bun/test/mock directory: 6 passed, 0 failed, 0 unsupported, 4 todo
• repository build and git diff --check: passed

The test uses the general mock registry + dynamic import path; no filename-specific result shim was added.

Completed on main in 7036b9d4486b385debc8b095883bada74a8fd464.