Added the Scene Manager (Libreflow casting, load, update, assetize)

New Scene Manager panel (WTD tab) talking to a running Libreflow through
its IPC server and the wtdcmds commands: pick the shot context, read the
casting, link the latest available publishes (overrides for chars and
props, collection instances otherwise), flag out-of-date versions in red,
update / roll back / remove loaded assets, and publish local collections
as assets. Requests run in the background. Settings in config.py
(SCENE_MANAGER_*, LIBREFLOW_*).

The Shot Viewer groups rigs loaded by the Scene Manager by asset type.
The manifest declares the network permission.

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

scene_manager/__init__.py

@@ -0,0 +1,15 @@
+"""Scene Manager: load, update and publish the assets of a shot through Libreflow.
+
+Libreflow is reached through its IPC server (``ipc``), the linked assets are
+handled in ``library`` and the operators in ``operators``.
+"""
+
+from . import operators
+
+
+def register():
+    operators.register()
+
+
+def unregister():
+    operators.unregister()