chore: checkpoint web Blender migration source, tools and docs

Accumulated uncommitted work: GHOST Web backend, WebGL/GPU web layer,
web workflow engine and protocol, tooling, docs and task records.
Large generated evidence, user-testing archives, build snapshots and
imported test assets remain untracked.

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

tools/web/native_preferences.py

@@ -0,0 +1,22 @@
+"""Load the Web Blender profile without touching the desktop user's config."""
+from pathlib import Path
+import bpy
+
+
+def load_preferences(root):
+    if (root / 'config' / 'userpref.blend').is_file():
+        state = bpy.ops.wm.read_userpref('EXEC_DEFAULT')
+        if 'FINISHED' not in state: raise RuntimeError('PREFERENCES_LOAD_FAILED')
+    # Persistence is an explicit Web session command, not shutdown of a temporary job.
+    bpy.context.preferences.use_preferences_save = False
+
+
+def save_preferences(root, sequence):
+    state = bpy.ops.wm.save_userpref('EXEC_DEFAULT')
+    if 'FINISHED' not in state: raise RuntimeError('PREFERENCES_SAVE_FAILED')
+    source = Path(bpy.utils.user_resource('CONFIG')) / 'userpref.blend'
+    if not source.is_file() or source.stat().st_size > 16 * 1024 * 1024:
+        raise RuntimeError('PREFERENCES_SAVE_OUTPUT_INVALID')
+    destination = root / f'preferences-{sequence:08d}.blend'
+    destination.write_bytes(source.read_bytes())
+    return destination