Is `flyteidl2.artifact.ArtifactService` served by the OSS `flyte-binary`, or is the artifact query API Union-hosted only?

Versions: SDK flyte==2.6.3, chart/binary flyte-binary v2.0.47, self-hosted on GKE Autopilot.

### What we observed
The SDK ships a full artifact registry surface `flyte.artifacts.new(...)` for publishing from tasks, and `flyte.remote.Artifact.get / listall / list_names` for querying — and the v2.0.46/47 releases extended the artifact protos (`ArtifactSpec.parent_artifact` lineage). Publishing appears to work: `flyte.artifacts.new` metadata is converted onto the output literal as `ProducedArtifact` (see `flyte/_internal/runtime/convert.py`) and tasks returning wrapped File outputs succeed.

But against a self-hosted `flyte-binary v2.0.47`, every query call fails with a route-level error:

```
flyte.remote.Artifact.get("published-name") -> ConnectError: Not Found
flyte.remote.Artifact.get("name-that-cannot-exist") -> ConnectError: Not Found (identical)
flyte.remote.Run.get("") -> works, same channel, same init
A published name and an impossible name failing identically suggests the service route is not registered, rather than the artifacts
```
being absent. helm show values flyte-binary --version v2.0.47 has no artifact-related flag to enable it.

### Questions
1. Is ArtifactService expected to be served by the OSS flyte-binary today, and if so, what did we miss enabling?
2. If not: is it on the OSS roadmap (for instance as part of the QueueService/RunService/ StateService split the backend README describes), or is the artifact query API intended to be Union-hosted only?
3. If publishing metadata flows from tasks but no query service is present, where does the ProducedArtifact metadata land on OSS — stored but unqueryable, or dropped?

Start by tracing ArtifactService route registration in the OSS flyte-binary and comparing it with the working flyte.remote.Run.get path. Inspect flyte/_internal/runtime/convert.py and the backend README, then check the v2.0.47 Helm values; done means establishing whether queries are served, how ProducedArtifact metadata is handled, and whether any configuration enables the service.

Written by the indexing model from the issue text.