Standardize variable naming conventions before CRAN #16
Description
Priority: P1
Variable names use inconsistent conventions: mixed suffixes (anymed vs diab_drug), ambiguous abbreviations (anymed — any med or any anti-HTN med?), and inconsistent use of snake_case. Renaming after CRAN publication requires deprecation cycles, so this should be resolved now.
PR #10 (AI.md) has a comprehensive snake_case proposal covering medications, status variables, and continuous measures. That's the starting point for discussion.