Implement Retire HoF (Gauntlet) rule enforcement for genlockes

When retireHoF is enabled, surviving HoF Pokemon and their evolutionary
families are retired at leg advancement and treated as duplicates in all
subsequent legs — both in the encounter modal and bulk randomize.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/src/app/alembic/versions/c3d4e5f6a7b9_add_retired_pokemon_ids_to_genlocke_legs.py

@@ -0,0 +1,30 @@
+"""add retired_pokemon_ids to genlocke_legs
+
+Revision ID: c3d4e5f6a7b9
+Revises: b2c3d4e5f6a8
+Create Date: 2026-02-09 18:00:00.000000
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects.postgresql import JSONB
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'c3d4e5f6a7b9'
+down_revision: Union[str, Sequence[str], None] = 'b2c3d4e5f6a8'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        'genlocke_legs',
+        sa.Column('retired_pokemon_ids', JSONB(), nullable=True),
+    )
+
+
+def downgrade() -> None:
+    op.drop_column('genlocke_legs', 'retired_pokemon_ids')