Fix loading adHocMeshes from dataset view mode (#8903)

Follow-up fix for #8708 (request must be by id now)

### URL of deployed dev instance (used for testing):
- https://fixadhocviewmode.webknossos.xyz

### Steps to test:
- Open a dataset with a static segmentation layer, request ad-hoc mesh
for a segment, should load.

### Issues:
- fixes
https://scm.slack.com/archives/C02H5T8Q08P/p1757351922621309?thread_ts=1757338710.530969&cid=C02H5T8Q08P

------
- [x] Added changelog entry (create a `$PR_NUMBER.md` file in
`unreleased_changes` or use `./tools/create-changelog-entry.py`)
- [x] Considered [common edge
cases](../blob/master/.github/common_edge_cases.md)

Author: fm3

frontend/javascripts/viewer/model/sagas/meshes/ad_hoc_mesh_saga.ts

@@ -442,10 +442,9 @@ function* maybeLoadMeshChunk(
   threeDMap.set(clippedPosition, true);
   const scaleFactor = yield* select((state) => state.dataset.dataSource.scale.factor);
   const dataStoreHost = yield* select((state) => state.dataset.dataStore.url);
-  const owningOrganization = yield* select((state) => state.dataset.owningOrganization);
-  const datasetDirectoryName = yield* select((state) => state.dataset.directoryName);
+  const datasetId = yield* select((state) => state.dataset.id);
   const tracingStoreHost = yield* select((state) => state.annotation.tracingStore.url);
-  const dataStoreUrl = `${dataStoreHost}/data/datasets/${owningOrganization}/${datasetDirectoryName}/layers/${
+  const dataStoreUrl = `${dataStoreHost}/data/datasets/${datasetId}/layers/${
     layer.fallbackLayer != null ? layer.fallbackLayer : layer.name
   }`;
   const tracingStoreUrl = `${tracingStoreHost}/tracings/volume/${layer.name}`;

unreleased_changes/8903.md

@@ -0,0 +1,2 @@
+### Fixed
+- Fixed loading ad-hoc-computed meshes for static segmentation layers.