Migrate pre-commit hooks from pre-commit to prek

Replace the Python-based pre-commit framework with prek (Rust) for
faster hook execution. Convert .pre-commit-config.yaml to prek.toml,
remove pre-commit from dev dependencies, and apply ruff auto-fixes
(UP037: remove unnecessary string quotes in type annotations).

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

backend/src/app/models/game.py

@@ -22,8 +22,8 @@ class Game(Base):
         ForeignKey("version_groups.id"), index=True
     )
 
-    version_group: Mapped["VersionGroup | None"] = relationship(back_populates="games")
-    runs: Mapped[list["NuzlockeRun"]] = relationship(back_populates="game")
+    version_group: Mapped[VersionGroup | None] = relationship(back_populates="games")
+    runs: Mapped[list[NuzlockeRun]] = relationship(back_populates="game")
 
     def __repr__(self) -> str:
         return f"<Game(id={self.id}, name='{self.name}')>"