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-seq-open-onmessage-probe.spec.ts

@@ -0,0 +1,42 @@
+import fs from "node:fs";
+import path from "node:path";
+import { test } from "@playwright/test";
+
+const root = path.resolve(import.meta.dirname, "../../..");
+
+test("capture onmessage error replies for compressed open", async ({ page }) => {
+  test.setTimeout(180_000);
+  await page.addInitScript(() => {
+    const scope = window as unknown as { __replies: unknown[] };
+    scope.__replies = [];
+    const proto = Worker.prototype as unknown as { __patched?: boolean };
+    if (proto.__patched) return;
+    proto.__patched = true;
+    const descriptor = Object.getOwnPropertyDescriptor(Worker.prototype, "onmessage");
+    if (!descriptor?.set) return;
+    Object.defineProperty(Worker.prototype, "onmessage", {
+      configurable: true,
+      enumerable: descriptor.enumerable,
+      get: descriptor.get,
+      set(value: ((event: MessageEvent) => unknown) | null) {
+        if (typeof value !== "function") return descriptor.set!.call(this, value);
+        const wrapped = (event: MessageEvent) => {
+          const data = event.data as { error?: { code?: string; message?: string; detail?: string } } | undefined;
+          if (data?.error) {
+            scope.__replies.push({ code: data.error.code, message: String(data.error.message).slice(0, 400), detail: String(data.error.detail ?? "").slice(0, 500) });
+            if (scope.__replies.length > 60) scope.__replies.shift();
+          }
+          return value(event);
+        };
+        return descriptor.set!.call(this, wrapped);
+      },
+    });
+  });
+  await page.goto("/");
+  await page.waitForTimeout(12000);
+  await page.evaluate(() => ((window as unknown as { __replies: unknown[] }).__replies = []));
+  await page.getByTestId("blend-file-input").setInputFiles(path.join(root, "blender-5.2.0/tests/files/sequence_editing/sequence.blend"));
+  await page.waitForTimeout(35000);
+  const replies = await page.evaluate(() => (window as unknown as { __replies: unknown[] }).__replies);
+  fs.writeFileSync("/tmp/seq-open-onmessage.json", JSON.stringify(replies, null, 2));
+});