Add judge_language config plumbing (settings + scenario + ScoreRequest)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

rag_eval/config/loader.py

@@ -64,6 +64,7 @@ def load_scenario(path: str | Path) -> Scenario:
         optimization_advisor=model.optimization_advisor,
         metric_weights=dict(model.metric_weights),
         doc_weights=dict(model.doc_weights),
+        judge_language=model.judge_language,
     )
     # Run cross-field checks after all relative paths have been resolved.
     validate_scenario(scenario)

rag_eval/config/schema.py

@@ -57,6 +57,7 @@ class ScenarioModel(BaseModel):
     optimization_advisor: bool = False
     metric_weights: dict[str, float] = Field(default_factory=dict)
     doc_weights: dict[str, float] = Field(default_factory=dict)
+    judge_language: Literal["en", "zh"] | None = None
 
     @field_validator("metrics")
     @classmethod