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-open-error-per-file.spec.ts

@@ -0,0 +1,40 @@
+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]> = [
+  ["blends", "blender-5.2.0/tests/files/sequence_editing/effects/blends.blend"],
+  ["sequence-gzip", "blender-5.2.0/tests/files/sequence_editing/sequence.blend"],
+];
+
+test("capture error per failing blend", async ({ page }) => {
+  test.setTimeout(300_000);
+  const out: Record<string, unknown> = {};
+  for (const [label, rel] of cases) {
+    await page.addInitScript(() => {
+      const scope = window as unknown as { __replies: unknown[] };
+      scope.__replies = [];
+      const descriptor = Object.getOwnPropertyDescriptor(Worker.prototype, "onmessage");
+      if (!descriptor?.set) return;
+      Object.defineProperty(Worker.prototype, "onmessage", {
+        configurable: true,
+        get: descriptor.get,
+        set(value: ((event: MessageEvent) => unknown) | null) {
+          if (typeof value !== "function") return descriptor.set!.call(this, value);
+          return descriptor.set!.call(this, (event: MessageEvent) => {
+            const data = event.data as { error?: { code?: string; message?: string } } | undefined;
+            if (data?.error) scope.__replies.push({ code: data.error.code, message: String(data.error.message).slice(0, 300) });
+            return value(event);
+          });
+        },
+      });
+    });
+    await page.goto("/");
+    await page.waitForTimeout(10000);
+    await page.getByTestId("blend-file-input").setInputFiles(path.join(root, rel));
+    await page.waitForTimeout(25000);
+    out[label] = await page.evaluate(() => (window as unknown as { __replies: unknown[] }).__replies);
+  }
+  fs.writeFileSync("/tmp/open-error-per-file.json", JSON.stringify(out, null, 2));
+});