Fix migration order: move gamerewards after player table

gamerewards has a FK to player (player_id), so it must be migrated
after the player table. Previously this caused the Pablo Sanchez Card
reward (id=9, player_id=9399) to fail with FK violation.

scripts/migrate_to_postgres.py

@@ -57,10 +57,11 @@ MIGRATION_ORDER = [
     # Tier 2: Simple FK dependencies (single level)
     "cardset",  # -> event
     "mlbplayer",  # no FKs
-    "gamerewards",  # -> packtype, player (but player not created yet, so nullable)
     # Tier 3: Core entity tables
     "team",  # -> event
     "player",  # -> cardset, rarity, mlbplayer
+    # Tier 3b: Tables dependent on player
+    "gamerewards",  # -> packtype, player
     # Tier 4: Dependent on core entities
     "pack",  # -> team, packtype, cardset
     "card",  # -> player, team, pack