Adds module-level label and cross-reference to the new doc.
TEST_EXPENSES_AGENT.md documents every test group, case, and the
real-world bug each test guards against (e.g. In-N-Out OCR mismatch).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
'Restaurant A' vs 'Restaurant Z' differ by 1 char so difflib scores
them at ~91% -- correctly above the 80% threshold. Use clearly
different vendors (Starbucks Coffee vs McDonalds Burger) instead.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>