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/models/genlocke.py

@@ -0,0 +1,46 @@
+from datetime import datetime
+
+from sqlalchemy import DateTime, ForeignKey, SmallInteger, String, UniqueConstraint
+from sqlalchemy.dialects.postgresql import JSONB
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+from sqlalchemy.sql import func
+
+from app.core.database import Base
+
+
+class Genlocke(Base):
+    __tablename__ = "genlockes"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    name: Mapped[str] = mapped_column(String(100))
+    status: Mapped[str] = mapped_column(String(20), index=True)  # active, completed, failed
+    genlocke_rules: Mapped[dict] = mapped_column(JSONB, default=dict)
+    nuzlocke_rules: Mapped[dict] = mapped_column(JSONB, default=dict)
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now()
+    )
+
+    legs: Mapped[list["GenlockeLeg"]] = relationship(
+        back_populates="genlocke", order_by="GenlockeLeg.leg_order"
+    )
+
+
+class GenlockeLeg(Base):
+    __tablename__ = "genlocke_legs"
+    __table_args__ = (
+        UniqueConstraint("genlocke_id", "leg_order", name="uq_genlocke_legs_order"),
+    )
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    genlocke_id: Mapped[int] = mapped_column(
+        ForeignKey("genlockes.id", ondelete="CASCADE"), index=True
+    )
+    game_id: Mapped[int] = mapped_column(ForeignKey("games.id"), index=True)
+    run_id: Mapped[int | None] = mapped_column(
+        ForeignKey("nuzlocke_runs.id"), index=True
+    )
+    leg_order: Mapped[int] = mapped_column(SmallInteger)
+
+    genlocke: Mapped["Genlocke"] = relationship(back_populates="legs")
+    game: Mapped["Game"] = relationship()
+    run: Mapped["NuzlockeRun | None"] = relationship()