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>

web/tests/fixtures/create-sequencer-scene-input.py

@@ -0,0 +1,18 @@
+import pathlib
+import bpy
+
+root = pathlib.Path(__file__).resolve().parents[3]
+target = root / "tests/files/web/sequencer_scene_source.blend"
+if target.exists():
+    raise RuntimeError("Retain the existing fixture; rebuild only when its recipe changes")
+bpy.ops.wm.open_mainfile(filepath=str(root / "tests/files/web/sequencer_scene.blend"))
+source = bpy.data.scenes.new("SourceScene")
+source.frame_start = 1
+source.frame_end = 48
+camera = bpy.data.objects.new("SourceCamera", bpy.data.cameras.new("SourceCamera"))
+source.collection.objects.link(camera)
+source.camera = camera
+source.world = bpy.data.worlds.new("SourceWorld")
+source.world.color = (0.15, 0.35, 0.55)
+bpy.context.window.scene = bpy.data.scenes["SequencerScene"]
+bpy.ops.wm.save_as_mainfile(filepath=str(target))