Clarify canonical ownership of the dbt converter

## Context

The dbt/MetricFlow ↔ Ossie converter was originally added under `dbt-labs/metricflow/metricflow/converters`, and is now maintained under `apache/ossie/converters/dbt` as the `apache-ossie-dbt` package.

The MetricFlow repository still contains the original `metricflow/converters` implementation, while the Ossie repository contains the newer `ossie_dbt` implementation.

## Question

Is `apache/ossie/converters/dbt` now the canonical implementation and ownership location for the dbt/MetricFlow ↔ Ossie converter?

If so, should the duplicate `metricflow/converters` implementation be deprecated and eventually removed from MetricFlow after a documented migration/release window?

Clarifying this would help avoid two implementations diverging and make it clear where future fixes and feature requests should be filed.

Start by comparing the implementations in dbt-labs/metricflow/metricflow/converters and apache/ossie/converters/dbt, including the apache-ossie-dbt package. Review the ownership and release context, then document which location is canonical and whether the MetricFlow implementation should be deprecated or removed after a migration window.

Written by the indexing model from the issue text.