Extract shared pitcher value computation into _pitcher_value() helper.
Consolidate duplicated column lists and index helper in season stats tests.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Separate batting and pitching into distinct tables with descriptive column
names. Eliminates naming collisions (so/k ambiguity) and column mismatches
between the ORM model and raw SQL. Each table now covers all aggregatable
fields from its source (BattingStat/PitchingStat) including sac, ibb, gidp,
earned_runs, runs_allowed, wild_pitches, balks, and games_started.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
The single-letter `k` field was ambiguous and too short for comfortable use.
Rename to `so_pitcher` for clarity, and `so` to `so_batter` to distinguish
batting strikeouts from pitching strikeouts in the same model.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
