Scene Manager: Load Publish and numbered instances

Load Publish (Loaded panel) searches every asset of the project, then
loads any of its published .blend files at any version, cast in the shot
or not. The file the casting would load and the latest version on this
site are preselected; a version not on this site is requested instead.
Built on the existing wtd_list_assets / wtd_get_asset_files /
wtd_get_revisions commands.

New instances are numbered (COL_bob_01, tree_01...), counting on from the
highest number in the file (SCENE_MANAGER_INSTANCE_NAME).

README: Pick Shot only lists shots that exist in Libreflow.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

dev/make_test_assets.py

@@ -6,6 +6,7 @@ bob: a rig (COL_bob: armature + meshes), v001 has 1 mesh, v002 has 2.
 tree: COL_tree holding only LOD collections (COL_tree_LOD0, COL_tree_LOD1), plus an
 unrelated top-level collection. v002 adds a mesh outside the LODs, v003 has no LOD.
 car: a rig, COL_car: armature + named LODs COL_car_LODlow, _LODhigh, _LODmid.
+chair: COL_chair (not cast, loaded with Load Publish).
 rock: a single top-level collection not named after the asset (fallback case), its mesh
 using a node group linked from Blender's essentials (an indirect library).
 """
@@ -67,4 +68,5 @@ write(os.path.join(lib, "tree", "v002", "model.blend"), "COL_tree", meshes=1, ex
 write(os.path.join(lib, "tree", "v003", "model.blend"), "COL_tree", meshes=1, extra=True)
 write(os.path.join(lib, "rock", "v001", "rock.blend"), "rock_geo", node_group=True)
 write(os.path.join(lib, "car", "v001", "car.blend"), "COL_car", meshes=0, rig=True, lods=["low", "high", "mid"])
+write(os.path.join(lib, "chair", "v001", "chair.blend"), "COL_chair")
 print("Test assets written in", lib)