Add genlocke creation wizard with backend API and 4-step frontend

Implements the genlocke creation feature end-to-end: Genlocke and
GenlockeLeg models with migration, POST /genlockes endpoint that
creates the genlocke with all legs and auto-starts the first run,
and a 4-step wizard UI (Name, Select Games with preset templates,
Rules, Confirm) at /genlockes/new.

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

backend/src/app/alembic/versions/b2c3d4e5f6a8_add_genlocke_tables.py

@@ -0,0 +1,46 @@
+"""add genlocke tables
+
+Revision ID: b2c3d4e5f6a8
+Revises: a1b2c3d4e5f8, b7c8d9e0f1a2
+Create Date: 2026-02-09 14:00:00.000000
+
+"""
+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 = 'b2c3d4e5f6a8'
+down_revision: Union[str, Sequence[str], None] = ('a1b2c3d4e5f8', 'b7c8d9e0f1a2')
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        'genlockes',
+        sa.Column('id', sa.Integer(), primary_key=True),
+        sa.Column('name', sa.String(100), nullable=False),
+        sa.Column('status', sa.String(20), nullable=False, index=True),
+        sa.Column('genlocke_rules', JSONB(), nullable=False, server_default='{}'),
+        sa.Column('nuzlocke_rules', JSONB(), nullable=False, server_default='{}'),
+        sa.Column('created_at', sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False),
+    )
+
+    op.create_table(
+        'genlocke_legs',
+        sa.Column('id', sa.Integer(), primary_key=True),
+        sa.Column('genlocke_id', sa.Integer(), sa.ForeignKey('genlockes.id', ondelete='CASCADE'), nullable=False, index=True),
+        sa.Column('game_id', sa.Integer(), sa.ForeignKey('games.id'), nullable=False, index=True),
+        sa.Column('run_id', sa.Integer(), sa.ForeignKey('nuzlocke_runs.id'), nullable=True, index=True),
+        sa.Column('leg_order', sa.SmallInteger(), nullable=False),
+        sa.UniqueConstraint('genlocke_id', 'leg_order', name='uq_genlocke_legs_order'),
+    )
+
+
+def downgrade() -> None:
+    op.drop_table('genlocke_legs')
+    op.drop_table('genlockes')