fix: resolve .js subpath types in Deno

[mikemikimike]

Summary

• add an explicit ./*.js export pattern so Deno maps .js subpaths to the emitted declaration files
• preserve Node ESM and CommonJS subpath resolution
• add a regression test for the export targets

Fixes #2701

Validation

• npm test -- --run test/issues/test_2701_deno_subpath_exports.test.ts
• npm run typecheck
• Windows-safe ESM/CJS TypeScript compilation
• targeted Prettier and ESLint checks pass
• full npm test ran 53 files / 1646 tests but exited 1 because two existing Windows stdio tests emitted unhandled JSON parse errors

[changeset-bot]

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Latest commit: 197ef19

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commit: 197ef19

[mikemikimike]

Closing this duplicate PR because Issue #2701 already has the existing open PR #2702 addressing the same fix. No further action is requested from maintainers.