fix: create mock user to resolve FK constraint issue

Issues fixed:
1. Frontend port is 3000 (not 5173)
2. Projects API returns 500 due to missing user
3. Foreign key constraint violation on projects_user_id_fkey

Solutions:
- Created create-mock-user.ts script
- Added user-mock-001 to database
- Created startup guide (娴嬭瘯鍜屽惎鍔?md)
- Created one-click launcher (涓€閿惎鍔?bat)
- Created diagnostic tool (璇婃柇闂.bat)

New files:
- backend/src/scripts/create-mock-user.ts
- 娴嬭瘯鍜屽惎鍔?md
- 涓€閿惎鍔?bat
- 璇婃柇闂.bat

backend/src/scripts/create-mock-user.ts

@@ -0,0 +1,43 @@
+import { PrismaClient } from '@prisma/client';
+
+const prisma = new PrismaClient();
+
+async function createMockUser() {
+  try {
+    console.log('🔄 正在创建模拟用户...');
+
+    // 检查用户是否已存在
+    const existingUser = await prisma.user.findUnique({
+      where: { id: 'user-mock-001' },
+    });
+
+    if (existingUser) {
+      console.log('✅ 模拟用户已存在');
+      console.log('用户信息:', existingUser);
+      return;
+    }
+
+    // 创建模拟用户
+    const user = await prisma.user.create({
+      data: {
+        id: 'user-mock-001',
+        email: 'demo@example.com',
+        password: 'mock-password-hash', // 模拟密码（实际应用需要加密）
+        name: '演示用户',
+        role: 'user',
+        status: 'active',
+      },
+    });
+
+    console.log('✅ 模拟用户创建成功！');
+    console.log('用户信息:', user);
+  } catch (error) {
+    console.error('❌ 创建模拟用户失败:', error);
+    process.exit(1);
+  } finally {
+    await prisma.$disconnect();
+  }
+}
+
+createMockUser();
+