feat: 添加动态获取系统标题功能

1. 后端新增公开系统设置接口，仅允许获取id为1或key为"系统标题"的配置项
2. 管理后台登录页和布局页改为动态获取系统标题作为页面标题
3. 两处页面均在挂载时调用接口获取系统标题并更新对应显示文本

backend/auth/apps/settings/urls.py

@@ -67,6 +67,30 @@ async def get_settings(
     return [SystemSettingResponse.model_validate(s) for s in settings]
 
 
+@router.get("/public", response_model=SystemSettingResponse)
+async def get_public_setting(
+    setting_id: int = None,
+    key: str = None,
+    db: AsyncSession = Depends(get_db),
+):
+    """公开接口：获取系统设置（仅允许获取id为1或key为"系统标题"的内容）"""
+    if setting_id is not None:
+        if setting_id != 1:
+            raise HTTPException(status_code=403, detail="无权访问该设置项")
+        result = await db.execute(select(SystemSetting).filter(SystemSetting.id == setting_id))
+    elif key is not None:
+        if key != "系统标题":
+            raise HTTPException(status_code=403, detail="无权访问该设置项")
+        result = await db.execute(select(SystemSetting).filter(SystemSetting.key == key))
+    else:
+        raise HTTPException(status_code=400, detail="必须提供setting_id或key参数")
+    
+    setting = result.scalar_one_or_none()
+    if not setting:
+        raise HTTPException(status_code=404, detail="设置项不存在")
+    return setting
+
+
 @router.get("/{setting_id}", response_model=SystemSettingResponse)
 async def get_setting(
     setting_id: int,

frontend/src/modules/admin/layout/AdminLayout.vue

@@ -1,7 +1,7 @@
 <template>
   <el-container class="admin-root">
     <el-aside width="220px" class="aside">
-      <div class="brand">BookSystem 管理</div>
+      <div class="brand">{{sysTitle}}</div>
       <el-menu
         :default-active="active"
         router
@@ -72,15 +72,17 @@
 </template>
 
 <script setup lang="ts">
-import { computed, onMounted } from "vue";
+import { computed, onMounted, ref } from "vue";
 import { useRoute, useRouter } from "vue-router";
 import { Key, Setting } from "@element-plus/icons-vue";
 import { ElMessage } from "element-plus";
 import { useAuthStore } from "@/modules/admin/stores/auth";
+import axios from "axios";
 
 const route = useRoute();
 const router = useRouter();
 const auth = useAuthStore();
+const sysTitle = ref("");
 
 const active = computed(() => route.path);
 const pageTitle = computed(() => (route.meta.title as string) || "");
@@ -105,8 +107,18 @@ const hasAnyPermission = computed(() => {
   return hasUserPermission.value || hasRolePermission.value || hasPermissionPermission.value;
 });
 
+async function getSysTitle() {
+  const baseURL = import.meta.env.VITE_API_BASE || "/api";
+  let res = await axios.get(`${baseURL}/settings/public?setting_id=1`)
+  if (res.data) {
+    sysTitle.value = res.data.value;
+  }
+}
+
+
 onMounted(async () => {
   try {
+    getSysTitle();
     if (!auth.user) {
       await auth.fetchProfile();
     }

frontend/src/modules/admin/views/LoginView.vue

@@ -2,7 +2,7 @@
   <div class="login-wrap">
     <el-card class="card" shadow="hover">
       <template #header>
-        <span class="card-title">管理后台登录</span>
+        <span class="card-title">{{ sysTitle }}</span>
       </template>
       <el-form ref="formRef" :model="form" :rules="rules" label-width="88px" @submit.prevent>
         <el-form-item label="用户名" prop="username">
@@ -57,6 +57,7 @@ const formRef = ref<FormInstance>();
 const loading = ref(false);
 const captchaUrl = ref("");
 const captchaId = ref("");
+const sysTitle = ref("");
 
 const baseURL = import.meta.env.VITE_API_BASE || "/api";
 
@@ -72,6 +73,13 @@ const rules: FormRules = {
   captcha_code: [{ required: true, message: "请输入验证码", trigger: "blur" }],
 };
 
+async function getSysTitle() {
+  let res = await axios.get(`${baseURL}/settings/public?setting_id=1`)
+  if (res.data) {
+    sysTitle.value = res.data.value;
+  }
+}
+
 async function loadCaptcha() {
   if (captchaUrl.value.startsWith("blob:")) {
     URL.revokeObjectURL(captchaUrl.value);
@@ -135,6 +143,7 @@ async function onSubmit() {
 
 onMounted(() => {
   loadCaptcha();
+  getSysTitle();
 });
 </script>