feat(Team): add isInLeagueTable and leagueTableRank fields with migration

backend/migrations/20260922_add_official_league_table_fields.sql

@@ -0,0 +1,5 @@
+-- Persist the participant list and rank supplied by the official click-TT table.
+-- Existing teams remain visible until their league table is refreshed once.
+ALTER TABLE team
+  ADD COLUMN is_in_league_table TINYINT(1) NOT NULL DEFAULT 1,
+  ADD COLUMN league_table_rank INT NULL;