feat: 添加 Admin 管理后台

- 数据库新增 Role 枚举、disabled 字段和 McpCallLog 调用日志表
- 后端新增 requireAdmin 中间件和 /api/admin/* 管理接口（统计、用户、项目、日志）
- MCP 工具调用自动记录详细日志（耗时、参数、响应大小、客户端IP、token估算）
- 前端新增 /admin 路由区域：仪表盘、用户管理、项目管理、调用日志四个页面
- JWT 携带 role 字段，登录/OAuth 增加禁用账号检查
- nginx 配置补充 X-Forwarded-For 透传真实客户端 IP

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

prisma/schema.prisma

@@ -7,12 +7,19 @@ datasource db {
   url      = env("DATABASE_URL")
 }
 
+enum Role {
+  USER
+  ADMIN
+}
+
 model User {
   id              String         @id @default(uuid())
   email           String         @unique
   passwordHash    String?
   name            String
   avatarUrl       String?
+  role            Role           @default(USER)
+  disabled        Boolean        @default(false)
   apiKeyHash      String?
   apiKeyEncrypted String?
   apiKeyPrefix    String?
@@ -33,8 +40,26 @@ model OAuthAccount {
   @@unique([provider, providerAccountId])
 }
 
+model McpCallLog {
+  id              String   @id @default(uuid())
+  projectId       String
+  toolName        String
+  calledAt        DateTime @default(now())
+  durationMs      Int
+  success         Boolean
+  requestParams   Json     @default("{}")
+  responseSize    Int      @default(0)
+  clientIp        String   @default("")
+  estimatedTokens Int?
+  project         Project  @relation(fields: [projectId], references: [id], onDelete: Cascade)
+
+  @@index([projectId])
+  @@index([calledAt])
+  @@index([toolName])
+}
+
 model Project {
-  id             String     @id @default(uuid())
+  id             String       @id @default(uuid())
   userId         String
   name           String
   description    String?
@@ -43,9 +68,10 @@ model Project {
   openApiVersion String
   createdAt      DateTime   @default(now())
   updatedAt      DateTime   @updatedAt
-  user           User       @relation(fields: [userId], references: [id], onDelete: Cascade)
+  user           User         @relation(fields: [userId], references: [id], onDelete: Cascade)
   modules        Module[]
   endpoints      Endpoint[]
+  mcpCallLogs    McpCallLog[]
 }
 
 enum ModuleSource {