chore: add live stat field population audit

[Mattsface]

Summary

Adds a developer-only live audit script for comparing MLB Stats API payload fields with values populated by python-mlb-statsapi models.

The audit classifies fields as:

• PASS — raw MLB value matches the parsed model value
• MLB OMITTED — model supports the field but MLB did not send it
• MODEL MISSING — MLB sent a key not represented by the parsed model
• PARSE FAILURE — MLB sent a non-null value but the model populated None
• MISMATCH — MLB and parsed values differ

Defaults to Aaron Judge, Shohei Ohtani, and Juan Soto for 2025 hitting season and seasonAdvanced stats. Players, season, group, and stat types can be overridden from the CLI.

This is intentionally not part of CI because it depends on the live MLB API.

Usage

poetry run python scripts/audit_stat_fields.py

Verbose output including passing fields:

poetry run python scripts/audit_stat_fields.py --verbose

Custom example:

poetry run python scripts/audit_stat_fields.py --season 2024 --stat season --player 592450:Judge

Context

This follows the investigation in #246, where airOuts was confirmed to be returned and populated correctly while flyOuts was omitted from the standard season payload.

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.