feat: OpenMesh 基础平台与 MD/PDF 转换技能

- 后端: coworker 智能体框架, WS API, 文件上传, 附件处理
- 前端: Open WebUI, 文件全量走 upload API (含 MD/TXT/JSON 等文本类)
- 技能: md-to-office (pandoc + wkhtmltopdf)
- 修复: 上传文件路径丢失, Agent 搜索浪费, 输出文件跑到 uploads/
- 打包: PyInstaller one-dir, 预打包 pandoc/wkhtmltopdf/chromium

surfaces/gui/e2e/composer-model-loading.spec.ts

@@ -0,0 +1,18 @@
+import { test, expect } from "./fixtures";
+
+// The composer must never advertise models the backend didn't confirm: before the
+// /v1/settings list arrives (cold app boot races the sidecar), the picker is a
+// disabled "Loading models…" chip — NOT a hardcoded fallback list, which went stale
+// and offered phantom ids (caught by owner, 2026-07-21).
+test("picker shows a disabled Loading-models chip until the list arrives", async ({ page }) => {
+  await page.route("**/v1/settings", (r) =>
+    r.fulfill({
+      json: { model: "gpt-5.5", models: [], model_labels: {}, has_key: true, model_ready: true, onboarded: true, nav_layout: "flat" },
+    }),
+  );
+  await page.goto("/");
+  const chip = page.getByTestId("models-loading");
+  await expect(chip).toBeVisible();
+  await expect(chip).toBeDisabled();
+  await expect(chip).toContainText("Loading models…");
+});