feat: add metric_weights and doc_weights to Scenario schema and dataclass

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

rag_eval/config/schema.py

@@ -55,6 +55,8 @@ class ScenarioModel(BaseModel):
     output_dir: str
     runtime: RuntimeConfigModel = Field(default_factory=RuntimeConfigModel)
     optimization_advisor: bool = False
+    metric_weights: dict[str, float] = Field(default_factory=dict)
+    doc_weights: dict[str, float] = Field(default_factory=dict)
 
     @field_validator("metrics")
     @classmethod