Build The Box-Score Prior Panel

Build the validated player-season panel first, then run:

uv run nba-build-box-score-prior-panel

The command atomically refreshes data/analytical/box_score_prior_panel/. It derives all dynamic features from the immediately preceding season and excludes the initial 1996-97 archive season from model-ready targets because it has no in-archive prior season.

The panel is a data-preparation artifact. It does not fit a box-score model or select predictive hyperparameters. See Box-Score Prior Panel for the contract and Box-Score RAPM Prior for the planned model program.