fix(ml): drop unnecessary quotes on MLSettings.load annotations (UP037)

Python 3.14 evaluates annotations lazily, so the self-referential return
type needs no forward-ref quotes — matches ImportSettings.load. Fixes the
ruff lint lane on the DRY-pass push.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NsmJSQxnNxGgtM5Yz4GAqi

backend/app/models/ml_settings.py

@@ -215,12 +215,12 @@ class MLSettings(Base):
     )
 
     @classmethod
-    async def load(cls, session) -> "MLSettings":
+    async def load(cls, session) -> MLSettings:
         """The singleton settings row (id=1), via an async session. Mirrors
         ImportSettings.load — the shared singleton-loader pattern."""
         return (await session.execute(select(cls).where(cls.id == 1))).scalar_one()
 
     @classmethod
-    def load_sync(cls, session) -> "MLSettings":
+    def load_sync(cls, session) -> MLSettings:
         """The singleton settings row (id=1), via a sync session."""
         return session.execute(select(cls).where(cls.id == 1)).scalar_one()