Add ML worker parser regression for OCR-noisy lab entries

[SahilKumar75]

Summary

Add a regression test for OCR-noisy lab timetable entries so parser behavior stays stable.

Scope

• Add a test case with noisy lab text, faculty code, and location text.
• Verify the parsed entry type, subject, location, and notes.
• Keep the test independent of external OCR binaries.

Acceptance Criteria

• The regression test fails before the parser improvement or protects existing behavior.
• pytest passes from ml-worker.
• No generated cache or coverage artifacts are committed.