Generates 25 PA (Gaboro DME, high challenge) and 25 NJ (Gaboro DME, high
challenge) synthetic CSV files. All 50 files pass normalizer ingestion
(50/50). Adds test-data/.gitignore override so CSV test sets are tracked
despite root-level *.csv exclusion.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>