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/budgets.post.ts

@@ -0,0 +1,33 @@
+import { defineEventHandler, readBody } from '#nitro';
+
+import { MOCK_BUDGETS } from '../../utils/mock-data';
+import { useResponseSuccess } from '../../utils/response';
+
+export default defineEventHandler(async (event) => {
+  const body = await readBody(event);
+
+  const newBudget = {
+    id: Date.now(),
+    userId: 1,
+    category: body.category,
+    categoryId: body.categoryId,
+    emoji: body.emoji,
+    limit: body.limit,
+    spent: body.spent || 0,
+    remaining: body.remaining || body.limit,
+    percentage: body.percentage || 0,
+    currency: body.currency,
+    period: body.period,
+    alertThreshold: body.alertThreshold,
+    description: body.description,
+    autoRenew: body.autoRenew,
+    overspendAlert: body.overspendAlert,
+    dailyReminder: body.dailyReminder,
+    monthlyTrend: body.monthlyTrend || 0,
+    createdAt: new Date().toISOString(),
+    isDeleted: false,
+  };
+
+  MOCK_BUDGETS.push(newBudget);
+  return useResponseSuccess(newBudget);
+});