fix(package): exclude python test artifacts

[YOMXXX]

Summary

• keep the Hermes runtime in the npm package while excluding Python __pycache__, .pyc, and test files
• add a package files regression test so the exclusions stay in place
• reduces the current dry-run package from 155 entries / 770,594 bytes to 145 entries / 703,237 bytes

Verification

• npx vitest run src/package-files.test.ts (RED before fix, green after)
• npm test
• npm run build
• npm pack --dry-run --json --silent
• git diff --check

[Maxwell-Code07]

Awesome work! 13 fixes in one batch covering Gateway hardening, embedding compatibility, Hermes memory injection, offload stability, and pipeline optimization — a very productive cleanup session 👏

We'll review and merge them one by one 🚀