feat(web): role-aware UI (badge, selector, toggle button, hide admin-only sections for members)

web/src/components/Navbar.vue

@@ -91,6 +91,9 @@
 
       <div v-if="session.currentUser.value" class="nav-user">
         <span class="nav-user-name">{{ session.currentUser.value.username }}</span>
+        <span class="nav-user-role" :class="`role-${session.currentUser.value.role}`">
+          {{ session.currentUser.value.role === 'admin' ? '管理员' : '成员' }}
+        </span>
         <button class="nav-user-logout" @click="onLogout" title="退出">
           <Icon icon="mdi:logout" />
         </button>
@@ -670,4 +673,11 @@ onUnmounted(() => {
   border-radius: var(--radius-sm);
   &:hover { background: var(--bg-secondary); color: var(--text-primary); }
 }
+
+.nav-user-role {
+  font-size: 11px; padding: 2px 6px; border-radius: 4px;
+  font-weight: 500;
+}
+.role-admin { background: rgba(99, 145, 226, 0.18); color: #6391e2; }
+.role-member { background: rgba(150, 150, 150, 0.18); color: var(--text-secondary); }
 </style>