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/auth/auth.module.ts

@@ -0,0 +1,28 @@
+import { Module } from '@nestjs/common'
+import { PassportModule } from '@nestjs/passport'
+import { JwtModule } from '@nestjs/jwt'
+import { ConfigModule, ConfigService } from '@nestjs/config'
+import { AuthService } from './auth.service'
+import { AuthController } from './auth.controller'
+import { WechatService } from './wechat.service'
+import { JwtStrategy } from './jwt.strategy'
+import { JwtAuthGuard } from './jwt-auth.guard'
+import { RolesGuard } from './roles.guard'
+
+@Module({
+  imports: [
+    PassportModule,
+    JwtModule.registerAsync({
+      imports: [ConfigModule],
+      inject: [ConfigService],
+      useFactory: (configService: ConfigService) => ({
+        secret: configService.getOrThrow<string>('JWT_SECRET'),
+        signOptions: { expiresIn: '7d' },
+      }),
+    }),
+  ],
+  controllers: [AuthController],
+  providers: [AuthService, WechatService, JwtStrategy, JwtAuthGuard, RolesGuard],
+  exports: [JwtStrategy, JwtAuthGuard, RolesGuard, AuthService],
+})
+export class AuthModule {}