init: 初始化 rclone-webgui 项目结构

外层仓库管理 webgui 源码、Docker 编排与项目文档；rclone 作为
git submodule 锁定在上游 master HEAD（59c86b01b），不携带任何
我们的改动。

- webgui/: webgui 源码（原本位于 rclone/cmd/webgui/）
  - web/: 原生 HTML/CSS/JS 静态前端（Anthropic 设计语言）
  - webgui.go: Go 子命令源码，仅当自行构建 rclone 二进制时需要
  - rclone-cmd-all-add-webgui-import.patch: 把 webgui 注册进
    rclone 的 cmd/all/all.go 的补丁，留作 fork 时使用
- rclone/: submodule → github.com/rclone/rclone，纯净不改动
- Dockerfile.webgui: 基于 nginx:1.27-alpine，从 ./webgui/web/
  COPY 静态资源
- docker/nginx.conf: SPA 静态托管 + 反向代理 RC API
  (/config/、/operations/、/sync/、/job/ 等) 与文件下载
  (/<remote>:<path>) 到 rclone rcd 容器，前端同源访问无 CORS
- docker-compose.yml: rclone (官方镜像 + rcd --rc-no-auth
  --rc-serve) + gui (nginx) 双服务编排，config 走 bind mount
  持久化
- DESIGN.md / CLAUDE.md / README.md: 文档
- .gitignore / .dockerignore: 排除 rclone.conf 等敏感文件，
  Docker 构建上下文只剩 webgui/web/ + nginx 配置（几十 KB）

webgui/web/assets/js/app.js

@@ -0,0 +1,62 @@
+// app.js — entry point. Routes hash changes to view renderers and
+// keeps the top-nav active state in sync.
+
+import { onRoute } from "./state.js";
+import { renderRemotes } from "./views/remotes.js";
+import { renderBrowse } from "./views/browser.js";
+import { renderJobs, renderNewJob, stopJobPolling } from "./views/jobs.js";
+import {
+  renderConfigureNew,
+  renderConfigureEdit,
+} from "./views/configure.js";
+
+const views = {
+  remotes: renderRemotes,
+  browse: renderBrowse,
+  jobs: renderJobs,
+  "jobs-new": renderNewJob,
+  "configure-new": renderConfigureNew,
+  "configure-edit": renderConfigureEdit,
+};
+
+function setActiveNav(routeName) {
+  const links = document.querySelectorAll("#nav-links a");
+  for (const a of links) {
+    const target = a.dataset.route;
+    let isActive = target === routeName;
+    // "Configure" is active on both configure-new and configure-edit
+    if (target === "configure" && routeName.startsWith("configure-")) {
+      isActive = true;
+    }
+    a.classList.toggle("active", isActive);
+  }
+}
+
+onRoute(async (route) => {
+  setActiveNav(route.name);
+
+  // Stop jobs polling when leaving the jobs view
+  if (route.name !== "jobs") {
+    stopJobPolling();
+  }
+
+  const renderer = views[route.name] || renderRemotes;
+  try {
+    await renderer(route.params);
+  } catch (e) {
+    console.error("view error", e);
+    const app = document.getElementById("app");
+    if (app) {
+      app.innerHTML = `<div class="empty"><h3>Something went wrong</h3><p>${escapeHtml(e.message)}</p></div>`;
+    }
+  }
+});
+
+function escapeHtml(s) {
+  return String(s)
+    .replace(/&/g, "&amp;")
+    .replace(/</g, "&lt;")
+    .replace(/>/g, "&gt;")
+    .replace(/"/g, "&quot;")
+    .replace(/'/g, "&#39;");
+}