fix: recognize missing Python stdlib modules

[naveenkumar982]

Closes #60

Summary

• recognize types and tomllib as Python standard-library imports
• add regression coverage for dotted stdlib imports and third-party near-misses

Validation

• Added a focused Node test covering the missing stdlib roots.
• I could not execute the repository test suite locally in this environment because a local checkout is unavailable; GitHub Actions should provide the authoritative build/test result.