Both PostAiCreateController::createMediaItem and
PostTemplateController::createMediaItem were doing:
$media = new Media([...]);
$media->mediable_type = Workspace::class; // ← FQCN literal
$media->mediable_id = $workspace->id;
$media->save();
Assigning Workspace::class directly bypasses the morphMap configured in
AppServiceProvider, so rows ended up with mediable_type =
'App\\Models\\Workspace' instead of the alias 'workspace'. Other queries
that pivot through the morphMap (e.g. $workspace->media) lose those
records on hosts where the FQCN doesn't match the alias.
Switch both to the relationship form:
$media = $workspace->media()->create([...]);
Laravel fills mediable_type via the morphMap, producing 'workspace'.
This is the same pattern AssetController and the HasMedia trait already
use; these two AI controllers were the only outliers (`grep -rn
'mediable_type =' app/` confirms).
Added tests/Unit/MediaPolymorphTest as a regression — asserts the
created row's mediable_type is the alias and that the relationship
resolves back to the workspace.
