feat: integrate WeChat Open Platform QR code login

- Add WeChat service for OAuth2 authentication flow
- Add WeChat routes (/api/wechat/login, /api/wechat/callback)
- Add WeChat types for login state and responses
- Update EntryQRCode component to support WeChat login
- Add WeChat config options (appId, appSecret, redirectUri)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/shared/src/types/index.ts

@@ -4,3 +4,4 @@ export * from './vote.types';
 export * from './draw.types';
 export * from './admin.types';
 export * from './scan-login.types';
+export * from './wechat.types';

packages/shared/src/types/wechat.types.ts

@@ -0,0 +1,54 @@
+// WeChat Open Platform login types
+
+export interface WechatLoginState {
+  state: string;
+  pcSocketId: string;
+  createdAt: number;
+  expiresAt: number;
+}
+
+export interface WechatLoginResponse {
+  success: boolean;
+  data?: {
+    authUrl: string;
+    state: string;
+    expiresAt: number;
+  };
+  error?: string;
+}
+
+export interface WechatCallbackResult {
+  success: boolean;
+  openid?: string;
+  pcSocketId?: string;
+  error?: string;
+}
+
+export interface WechatAccessTokenResponse {
+  access_token?: string;
+  expires_in?: number;
+  refresh_token?: string;
+  openid?: string;
+  scope?: string;
+  errcode?: number;
+  errmsg?: string;
+}
+
+export interface WechatUserInfo {
+  openid: string;
+  nickname?: string;
+  sex?: number;
+  province?: string;
+  city?: string;
+  country?: string;
+  headimgurl?: string;
+  privilege?: string[];
+  unionid?: string;
+}
+
+export interface WechatLoginSuccessPayload {
+  openid: string;
+  sessionToken: string;
+  userId: string;
+  userInfo?: WechatUserInfo;
+}