feat(server): add auth, user, and studio modules

Auth: WeChat login, JWT, roles guard (24 tests passing)
User: profile CRUD, training stats with month/total calculations
Studio: config management with auto-default creation

packages/server/src/app.module.ts

@@ -2,6 +2,9 @@ import { Module } from '@nestjs/common'
 import { ConfigModule } from '@nestjs/config'
 import { AppController } from './app.controller'
 import { PrismaModule } from './prisma/prisma.module'
+import { UserModule } from './user/user.module'
+import { AuthModule } from './auth/auth.module'
+import { StudioModule } from './studio/studio.module'
 
 @Module({
   imports: [
@@ -10,6 +13,9 @@ import { PrismaModule } from './prisma/prisma.module'
       envFilePath: ['.env.local', '.env'],
     }),
     PrismaModule,
+    AuthModule,
+    UserModule,
+    StudioModule,
   ],
   controllers: [AppController],
 })