feat: 完成全量功能开发，包括前端管理后台与后端服务优化

此提交实现了完整的知识库管理系统：
1. 新增Vue3 + Antd Vue前端管理后台，包含登录、文档管理、检索、类目设置等完整页面
2. 重构后端LLM调用抽象层，支持Ollama与OpenAI兼容服务动态切换
3. 调整默认嵌入模型配置为本地bge-m3模式
4. 优化入库任务去重逻辑与缓存清理机制
5. 完善Docker镜像构建与docker-compose部署配置
6. 修复多项测试用例与兼容性问题
7. 新增运行时配置API，支持动态调整系统参数

frontend/src/stores/useAuthStore.js

@@ -0,0 +1,66 @@
+import { defineStore } from 'pinia'
+
+const TOKEN_STORAGE_KEY = 'qmd_token'
+const USER_STORAGE_KEY = 'qmd_user'
+
+/**
+ * 从 localStorage 读取用户信息
+ * @returns {{username:string, role:string, created_at?:string} | null}
+ */
+function loadUserFromStorage() {
+  try {
+    const raw = localStorage.getItem(USER_STORAGE_KEY)
+    if (!raw) return null
+    const parsed = JSON.parse(raw)
+    if (parsed && typeof parsed === 'object' && parsed.username) {
+      return parsed
+    }
+    return null
+  } catch {
+    return null
+  }
+}
+
+export const useAuthStore = defineStore('auth', {
+  state: () => ({
+    token: localStorage.getItem(TOKEN_STORAGE_KEY) || '',
+    user: loadUserFromStorage()
+  }),
+
+  getters: {
+    isAuthenticated: (state) => Boolean(state.token),
+    isAdmin: (state) => state.user?.role === 'admin',
+    displayName: (state) => {
+      if (!state.user) return ''
+      return `${state.user.username} (${state.user.role})`
+    }
+  },
+
+  actions: {
+    /**
+     * 登录成功后保存 token + user
+     * @param {{access_token:string, user:object}} data
+     */
+    setAuth(data) {
+      this.token = data.access_token
+      this.user = data.user
+      localStorage.setItem(TOKEN_STORAGE_KEY, data.access_token)
+      localStorage.setItem(USER_STORAGE_KEY, JSON.stringify(data.user))
+    },
+
+    /** 清除登录态（登出 / 401） */
+    clearAuth() {
+      this.token = ''
+      this.user = null
+      localStorage.removeItem(TOKEN_STORAGE_KEY)
+      localStorage.removeItem(USER_STORAGE_KEY)
+    },
+
+    /**
+     * 登出
+     */
+    logout() {
+      this.clearAuth()
+    }
+  }
+})