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/transactions.post.ts

@@ -0,0 +1,33 @@
+import { readBody } from 'h3';
+
+import { createTransaction } from '~/utils/finance-repository';
+import { useResponseError, useResponseSuccess } from '~/utils/response';
+
+const DEFAULT_CURRENCY = 'CNY';
+
+export default defineEventHandler(async (event) => {
+  const body = await readBody(event);
+
+  if (!body?.type || !body?.amount || !body?.transactionDate) {
+    return useResponseError('缺少必填字段', -1);
+  }
+
+  const amount = Number(body.amount);
+  if (Number.isNaN(amount)) {
+    return useResponseError('金额格式不正确', -1);
+  }
+
+  const transaction = createTransaction({
+    type: body.type,
+    amount,
+    currency: body.currency ?? DEFAULT_CURRENCY,
+    categoryId: body.categoryId ?? null,
+    accountId: body.accountId ?? null,
+    transactionDate: body.transactionDate,
+    description: body.description ?? '',
+    project: body.project ?? null,
+    memo: body.memo ?? null,
+  });
+
+  return useResponseSuccess(transaction);
+});