添加书架刷新按钮 + 后端服务保活方案

前端:
- 书架筛选栏新增「↻ 刷新」按钮，点击重新加载分类和书架数据
- 新增 refreshShelf() 函数，带 loading 状态反馈
- 新增 .shelf-refresh-btn CSS 样式

后端保活:
- 新增 start_server.sh 启动脚本 (start/daemon/stop/restart/status)
- 新增 com.weread-dashboard.plist launchd 服务配置
  - KeepAlive=true: 崩溃自动重启
  - RunAtLoad=true: 开机自动启动
  - 日志输出到 /tmp/weread_server.log

static/js/app.js

@@ -318,6 +318,23 @@ function filterByCategory(fullCategory) {
     loadShelf(1);
 }
 
+// ===== 书架刷新 =====
+
+async function refreshShelf() {
+    const btn = document.getElementById("shelfRefreshBtn");
+    btn.disabled = true;
+    btn.classList.add("loading");
+    btn.textContent = "↻ 刷新中...";
+    try {
+        await loadShelfCategories();
+        await loadShelf(1);
+    } finally {
+        btn.disabled = false;
+        btn.classList.remove("loading");
+        btn.textContent = "↻ 刷新";
+    }
+}
+
 // ===== 初始化 =====
 
 document.addEventListener("DOMContentLoaded", async () => {