Templates previously referenced specific sports seasons (e.g. "NFL 2026"), requiring
admins to create a new template every year. Templates now reference sports directly
(e.g. "NFL") and resolve to the currently-draftable season at league-creation time.
- Remove `year` field from season_templates table
- Replace `sportsSeasonId` FK with `sportId` FK in season_template_sports
- applySportsFromTemplate now resolves each sport to its active draftable season
- Admin template UI updated to manage sports (not specific seasons)
- sports-data-sync export/import updated to the new sport-centric format
https://claude.ai/code/session_01CoRLHERakMncbPs877izvw
