feature comparison with nfl_data_py

[tanho63]

API changes:

• function naming now aligns with nflreadr, so import_ prefix now mostly swapped for load_ prefix
• uses polars instead of pandas
• caching reimplemented

Function comparisons:

• import_pbp_data() -> load_pbp()
• import_weekly_data() -> load_player_stats()
• import_seasonal_data() -> now handled in a standardized way via load_player_stats()
• import_snap_counts() -> load_snap_counts()
• import_ngs_data() -> load_nextgen_stats()
• import_officials() -> load_officials()
• import_schedules() -> load_schedules()
• import_seasonal_rosters() -> load_rosters()
• import_weekly_rosters() -> load_rosters_weekly()
• import_players() -> load_players()
• import_depth_charts() -> load_depth_charts()
• import_ids() -> load_ff_playerids()
• import_contracts() -> load_contracts()
• import_draft_picks() -> load_draft_picks()
• import_combine_data() -> load_combine()
• import_ftn_data() -> load_ftn_charting()
• import_injuries() -> load_injuries() (currently broken for 2025)
• import_qbr() -> not handled yet, see feature comparison with nflreadr v1.5.0 #2 for status
• import_seasonal_pfr() -> not handled yet, see feature comparison with nflreadr v1.5.0 #2 for status
• import_weekly_pfr() -> not handled yet, see feature comparison with nflreadr v1.5.0 #2 for status
• import_win_totals() -> not planned, data not part of nflverse
• import_sc_lines() -> not planned, currently not in nflreadr
• import_draft_values() -> not planned, currently not in nflreadr
• see_pbp_cols() -> not planned, use nflreadr dictionaries
• see_weekly_cols() -> not planned, use nflreadr dictionaries
• import_team_desc() -> not handled yet, see feature comparison with nflreadr v1.5.0 #2 for status
• cache_pbp() -> now handled via config options
• clean_nfl_data() -> see feature comparison with nflreadr v1.5.0 #2 for status of clean_player_names(), clean_team_abbrs()