Restrict zoom to selected imagery max zoom

When a selected imagery mosaic has a max-zoom, the platform should either restrict the user's ability to zoom in past the imagery available, or keep the imagery and enlarge. Currently, the platform removes the mosaic imagery and displays the baselayer imagery after zooming in past the mosiac max-zoom. This can cause confusion for users when engaging in retraining or inspection of results.

The issue names no files, tests, or entry points. Start by locating the selected imagery mosaic zoom handling in the frontend, then reproduce zooming beyond the mosaic max-zoom and establish whether the imagery should remain enlarged or zooming should be restricted; done means the baselayer imagery no longer unexpectedly replaces the selected mosaic.

Written by the indexing model from the issue text.