observability-pydantic-config-pydantic-v2-emits-userwarning-valid-config-keys-ha-af97bace

THEN Replace the deprecated `class Config: fields = {...}` with `model_config = {"populate_by_name": True}` and use `Field(alias=...)` on each model field to set aliases. This aligns with Pydantic V2 conventions and silences the warning.

# Before (v1 style)
class MyModel(BaseModel):
    field1: str
    class Config:
        fields = {"field1": {"alias": "alias1"}}

# After (v2 style)
from pydantic import Field
class MyModel(BaseModel):
    field1: str = Field(alias="alias1")
    model_config = {"populate_by_name": True}