Scene Manager: LOD switching; Shot Viewer renamed Shot Manager

LODs are child collections of the asset collection (COL_{asset}_LOD{n}).
Overrides hide the other LOD collections (viewport and render), keeping
the rig, pose and animation; collection instances instance the LOD
collection. Each instance has its own LOD, set per instance or for the
selection in the Loaded panel, kept through save, reload and updates.
Loading shows SCENE_MANAGER_DEFAULT_LOD (0).

The Shot Viewer panel is now "Shot Manager" and starts closed. Code
names and SHOT_VIEWER_* config keys are unchanged.

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

shot_viewer.py

@@ -1,4 +1,4 @@
-"""Shot viewer: switch, add and delete the shots of the scene from the sidebar.
+"""Shot manager: switch, add and delete the shots of the scene from the sidebar.
 
 Shots are the timeline markers bound to a camera (Ctrl+B in the timeline). A
 shot runs from its marker to the frame before the next camera marker, the last