feat: 实现基础设施层

axios 请求封装及七个业务模块 API，Pinia 状态管理（auth/system/models/tools），Mock 适配器与数据，以及流式对话、轮询、倒计时组合式函数。

frontend/src/stores/tools.ts

@@ -0,0 +1,48 @@
+import { defineStore } from 'pinia'
+import { ref, watch } from 'vue'
+import type { CustomTool } from '@/types'
+
+/**
+ * 自定义工具 store（localStorage 持久化）
+ * 原 web 项目 customTools 仅存本地，无后端
+ */
+export const useToolsStore = defineStore('tools', () => {
+  const STORAGE_KEY = 'customTools'
+  const tools = ref<CustomTool[]>(loadFromStorage())
+
+  function loadFromStorage(): CustomTool[] {
+    try {
+      return JSON.parse(localStorage.getItem(STORAGE_KEY) || '[]')
+    } catch {
+      return []
+    }
+  }
+
+  // 持久化
+  watch(
+    tools,
+    (val) => {
+      localStorage.setItem(STORAGE_KEY, JSON.stringify(val))
+    },
+    { deep: true },
+  )
+
+  function addTool(tool: CustomTool) {
+    tools.value.push(tool)
+  }
+
+  function updateTool(id: string, data: Partial<CustomTool>) {
+    const idx = tools.value.findIndex((t) => t.id === id)
+    if (idx !== -1) tools.value[idx] = { ...tools.value[idx], ...data }
+  }
+
+  function removeTool(id: string) {
+    tools.value = tools.value.filter((t) => t.id !== id)
+  }
+
+  function getTool(id: string): CustomTool | undefined {
+    return tools.value.find((t) => t.id === id)
+  }
+
+  return { tools, addTool, updateTool, removeTool, getTool }
+})