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/e2e/b3-pack-setpath-probe.spec.ts

@@ -0,0 +1,52 @@
+import fs from "node:fs";
+import path from "node:path";
+import { test } from "@playwright/test";
+import { NativeUIWorkflow, observeNative } from "../fixtures/native-ui-workflow";
+
+const root = path.resolve(import.meta.dirname, "../../..");
+const fixture = path.join(root, "blender-5.2.0/tests/files/sequence_editing/effects/fx_comp.blend");
+const mask = fs.readFileSync(path.join(root, "blender-5.2.0/tests/files/sequence_editing/effects/mask.png"));
+
+test("probe pack_all after assigning bpy.data.filepath", async ({ page }, testInfo) => {
+  test.setTimeout(180_000);
+  await observeNative(page);
+  await page.goto("/");
+  const flow = new NativeUIWorkflow(page, testInfo.outputPath("cases"));
+  await flow.command(() => page.getByTestId("blend-file-input").setInputFiles(fixture));
+  const out = await page.evaluate(async (maskBase64) => {
+    const worker = (window as any).__nativeWorkflowEngine as Worker;
+    const send = (command: any) => new Promise<any>((resolve, reject) => {
+      const requestId = `sp-${crypto.randomUUID()}`;
+      const receive = (event: MessageEvent) => {
+        if (event.data?.requestId !== requestId || event.data?.kind !== 'result') return;
+        worker.removeEventListener('message', receive);
+        if (event.data.ok) resolve(event.data.result); else reject(new Error(`${event.data.error?.code ?? 'NATIVE'}: ${event.data.error?.message ?? JSON.stringify(event.data.error)}`));
+      };
+      worker.addEventListener('message', receive); worker.postMessage({ requestId, command });
+    });
+    const log: any = {};
+    try {
+      const r = await send({ type: 'jsonCommand', cmd: 'pythonExec', params: {
+        filename: 'SetPath.py', console: false,
+        source: [
+          "import bpy, os, base64",
+          "root = '/browser/pack-case'",
+          "os.makedirs(root, exist_ok=True)",
+          "open(root + '/mask.png', 'wb').write(base64.b64decode('" + maskBase64 + "'))",
+          "print('STAGED', sorted(os.listdir(root)))",
+          "bpy.data.filepath = root + '/fx_comp.blend'",
+          "print('FILEPATH', repr(bpy.data.filepath))",
+          "print('ABS', bpy.path.abspath('//mask.png'), os.path.exists(bpy.path.abspath('//mask.png')))",
+          "print('BEFORE', [(i.name, i.packed_file is not None) for i in bpy.data.images])",
+          "print('PACK', bpy.ops.file.pack_all())",
+          "print('AFTER', [(i.name, i.packed_file is not None, i.packed_file.size if i.packed_file else None) for i in bpy.data.images])",
+        ].join("\n"),
+      } });
+      log.state = r.json?.state;
+      log.output = String(r.json?.output ?? '').slice(0, 2500);
+      log.revision = r.snapshot?.revision;
+    } catch (e: any) { log.error = String(e?.message ?? e); }
+    return log;
+  }, mask.toString("base64"));
+  fs.writeFileSync("/tmp/pack-setpath-probe.json", JSON.stringify(out, null, 2));
+});