refactor: 整合财务系统到主应用并重构后端架构

主要变更:
- 将独立的 web-finance 应用整合到 web-antd 主应用中
- 重命名 backend-mock 为 backend,增强后端功能
- 新增财务模块 API 端点(账户、预算、类别、交易)
- 增强财务仪表板和报表功能
- 添加 SQLite 数据存储支持和财务数据导入脚本
- 优化路由结构,删除冗余的 finance-system 模块

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

apps/backend/api/finance/accounts.get.ts

@@ -0,0 +1,17 @@
+import { getQuery } from 'h3';
+
+import { listAccounts } from '~/utils/finance-metadata';
+import { useResponseSuccess } from '~/utils/response';
+
+export default defineEventHandler(async (event) => {
+  const query = getQuery(event);
+  const currency = query.currency as string | undefined;
+
+  let accounts = listAccounts();
+
+  if (currency) {
+    accounts = accounts.filter((account) => account.currency === currency);
+  }
+
+  return useResponseSuccess(accounts);
+});