Add Hall of Fame team selection for completed runs

After marking a run as completed, a modal prompts the player to select
which Pokemon (up to 6) entered the Hall of Fame. The selection is stored
as hof_encounter_ids on the run, displayed in the victory banner, and
can be edited later. This lays the foundation for scoping genlocke
retireHoF to only the actual HoF team.

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

backend/src/app/alembic/versions/d4e5f6a7b9c0_add_hof_encounter_ids_to_nuzlocke_runs.py

@@ -0,0 +1,30 @@
+"""add hof_encounter_ids to nuzlocke_runs
+
+Revision ID: d4e5f6a7b9c0
+Revises: c3d4e5f6a7b9
+Create Date: 2026-02-09 20:00:00.000000
+
+"""
+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 = 'd4e5f6a7b9c0'
+down_revision: Union[str, Sequence[str], None] = 'c3d4e5f6a7b9'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        'nuzlocke_runs',
+        sa.Column('hof_encounter_ids', JSONB(), nullable=True),
+    )
+
+
+def downgrade() -> None:
+    op.drop_column('nuzlocke_runs', 'hof_encounter_ids')