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-old-version-matrix.spec.ts

@@ -0,0 +1,26 @@
+import fs from "node:fs";
+import path from "node:path";
+import { test } from "@playwright/test";
+
+const root = path.resolve(import.meta.dirname, "../../..");
+const cases: Array<[string, string]> = [
+  ["sequence-audio-257", "blender-5.2.0/tests/files/sequence_editing/sequence_audio.blend"],
+  ["softbody-basics-266", "blender-5.2.0/tests/files/physics/softbody_basics.blend"],
+  ["clothtest-257", "blender-5.2.0/tests/files/physics/clothtest.blend"],
+];
+
+test("old version blends open", async ({ page }) => {
+  test.setTimeout(420_000);
+  const out: Record<string, unknown> = {};
+  for (const [label, rel] of cases) {
+    await page.goto("/");
+    await page.waitForTimeout(12000);
+    await page.getByTestId("blend-file-input").setInputFiles(path.join(root, rel));
+    await page.waitForTimeout(28000);
+    out[label] = await page.evaluate(() => ({
+      status: document.querySelector('[data-testid="engine-status"]')?.textContent ?? "",
+      projectId: (document.querySelector("main.blender-app") as HTMLElement | null)?.dataset.projectId ?? "",
+    }));
+  }
+  fs.writeFileSync("/tmp/old-version-matrix.json", JSON.stringify(out, null, 2));
+});