refactor: generalize NatsOperationConsumer over the event model

import structlog

from nats.aio.client import Client

from nats.aio.subscription import Subscription

from pydantic import ValidationError

from pydantic import BaseModel, ValidationError

from open_exposure_gateway.core.config import NatsSettings

from open_exposure_gateway.domain.srm_events import SRMOperationCompleted

        self,

        client: Client,

        subject: str,

        handler: Callable[[SRMOperationCompleted], Awaitable[None]] | None = None,

        handler: Callable[[Any], Awaitable[None]] | None = None,

        event_model: type[BaseModel] = SRMOperationCompleted,

    ) -> None:

        self._client = client

        self._subject = subject

        self._handler = handler

        self._event_model = event_model

        self._subscription: Subscription | None = None

    async def start(self) -> None:

        try:

            event = SRMOperationCompleted.model_validate(raw)

            event = self._event_model.model_validate(raw)

        except ValidationError as exc:

            logger.warning("invalid_operation_completed_event", subject=msg.subject, error=str(exc))

            return

        try:

            await self._handler(event)

        except Exception:

            logger.exception("operation_completed_handler_failed", operation_id=event.operation_id)

            logger.exception(

                "operation_completed_handler_failed",

                operation_id=getattr(event, "operation_id", None),

            )