feat(frontend): 左栏 10 项按写作/资料库/审阅/更多分组（UX P2-1）

navSections(projectId?) 纯函数把平铺项目项归为四组，NavItems 复用「本作」小标题模式逐组渲染；链接/路由/激活键不变，工具箱收进「更多」不丢入口。

apps/web/components/NavItems.tsx

@@ -1,5 +1,6 @@
 "use client";
 
+import { Fragment } from "react";
 import Link from "next/link";
 import {
   Blocks,
@@ -19,9 +20,8 @@ import {
 import { usePathname } from "next/navigation";
 
 import {
-  GLOBAL_NAV_ITEMS,
   isNavItemActive,
-  projectNavItems,
+  navSections,
   type ActiveNav,
   type NavItem,
 } from "@/lib/nav/items";
@@ -36,35 +36,32 @@ interface NavItemsProps {
 }
 
 // 导航条目列表（桌面静态侧栏与移动抽屉共用，避免渲染漂移）。
+// 项目内页把 10 项按 写作/资料库/审阅/更多 分组（P2-1），每组一个小标题；全局组无标题直显于顶部。
 export function NavItems({ projectId, activeNav, onNavigate }: NavItemsProps) {
   const pathname = usePathname() ?? "/";
-  const scoped = projectId ? projectNavItems(projectId) : [];
+  const sections = navSections(projectId);
 
   return (
     <ul className="flex flex-col gap-1 px-2">
-      {GLOBAL_NAV_ITEMS.map((item) => (
-        <NavLink
-          key={item.label}
-          item={item}
-          active={isNavItemActive(item, { pathname, activeNav })}
-          onNavigate={onNavigate}
-        />
-      ))}
-      {scoped.length > 0 ? (
-        <li
-          className="mt-3 px-3 pb-1 text-xs font-semibold uppercase tracking-wide text-ink-soft/60"
-          aria-hidden="true"
-        >
-          本作
-        </li>
-      ) : null}
-      {scoped.map((item) => (
-        <NavLink
-          key={item.label}
-          item={item}
-          active={isNavItemActive(item, { pathname, activeNav })}
-          onNavigate={onNavigate}
-        />
+      {sections.map((section) => (
+        <Fragment key={section.label ?? "__global"}>
+          {section.label !== null ? (
+            <li
+              className="mt-3 px-3 pb-1 text-xs font-semibold uppercase tracking-wide text-ink-soft/60"
+              aria-hidden="true"
+            >
+              {section.label}
+            </li>
+          ) : null}
+          {section.items.map((item) => (
+            <NavLink
+              key={item.label}
+              item={item}
+              active={isNavItemActive(item, { pathname, activeNav })}
+              onNavigate={onNavigate}
+            />
+          ))}
+        </Fragment>
       ))}
     </ul>
   );