feat: 初始化 ChatGPT Team 管理机器人

核心功能:
- 实现基于 Telegram Inline Button 交互的后台面板与用户端
- 支持通过账密登录和 RT (Refresh Token) 方式添加 ChatGPT Team 账号
- 支持管理、拉取和删除待处理邀请，支持一键清空多余邀请
- 支持按剩余容量自动生成邀请兑换码，支持分页查看与一键清空未使用兑换码
- 随机邀请功能：成功拉人后自动核销兑换码
- 定时检测 Token 状态，实现自动续订/刷新并拦截封禁账号 (处理 401/402 错误)

系统与配置:
- 使用 PostgreSQL 数据库管理账号、邀请和兑换记录
- 支持在端内动态添加、移除管理员
- 完善 Docker 部署配置与 .gitignore 规则

internal/redeem/redeem.go

@@ -0,0 +1,139 @@
+package redeem
+
+import (
+	"fmt"
+	"math/rand"
+	"regexp"
+	"strings"
+
+	"go-helper/internal/chatgpt"
+	"go-helper/internal/database"
+	"go-helper/internal/model"
+)
+
+var (
+	emailRegex = regexp.MustCompile(`^[^\s@]+@[^\s@]+\.[^\s@]+$`)
+	codeRegex  = regexp.MustCompile(`^[A-Z0-9]{4}-[A-Z0-9]{4}-[A-Z0-9]{4}$`)
+	codeChars  = []byte("ABCDEFGHJKLMNPQRSTUVWXYZ23456789") // exclude confusable chars
+)
+
+// RedeemResult contains information about a successful redemption.
+type RedeemResult struct {
+	AccountEmail string
+	InviteOK     bool
+	Message      string
+}
+
+// Redeem validates the code, finds an available account, and sends an invite.
+func Redeem(db *database.DB, client *chatgpt.Client, code, email string, capacity int) (*RedeemResult, error) {
+	email = strings.TrimSpace(strings.ToLower(email))
+	code = strings.TrimSpace(strings.ToUpper(code))
+
+	if email == "" {
+		return nil, fmt.Errorf("请输入邮箱地址")
+	}
+	if !emailRegex.MatchString(email) {
+		return nil, fmt.Errorf("邮箱格式不正确")
+	}
+	if code == "" {
+		return nil, fmt.Errorf("请输入兑换码")
+	}
+	if !codeRegex.MatchString(code) {
+		return nil, fmt.Errorf("兑换码格式不正确（格式：XXXX-XXXX-XXXX）")
+	}
+
+	// 1. Look up the code.
+	rc, err := db.GetCodeByCode(code)
+	if err != nil {
+		return nil, fmt.Errorf("兑换码不存在或已失效")
+	}
+	if rc.IsRedeemed {
+		return nil, fmt.Errorf("该兑换码已被使用")
+	}
+
+	// 2. Find a usable account.
+	var account *model.GptAccount
+
+	if rc.AccountEmail != "" {
+		// Code is bound to a specific account.
+		accounts, err := db.GetOpenAccounts(capacity + 100) // get all open
+		if err != nil {
+			return nil, fmt.Errorf("查找账号失败: %v", err)
+		}
+		for i := range accounts {
+			if strings.EqualFold(accounts[i].Email, rc.AccountEmail) {
+				if accounts[i].UserCount+accounts[i].InviteCount < capacity {
+					account = &accounts[i]
+				}
+				break
+			}
+		}
+		if account == nil {
+			return nil, fmt.Errorf("该兑换码绑定的账号不可用或已满")
+		}
+	} else {
+		// Find any open account with capacity.
+		accounts, err := db.GetOpenAccounts(capacity)
+		if err != nil || len(accounts) == 0 {
+			return nil, fmt.Errorf("暂无可用账号，请稍后再试")
+		}
+		account = &accounts[0]
+	}
+
+	// 3. Send invite.
+	inviteErr := client.InviteUser(email, account)
+
+	// 4. Mark code as redeemed regardless of invite outcome.
+	if err := db.RedeemCode(rc.ID, email); err != nil {
+		return nil, fmt.Errorf("更新兑换码状态失败: %v", err)
+	}
+
+	// 5. Sync counts.
+	syncCounts(db, client, account)
+
+	result := &RedeemResult{AccountEmail: account.Email}
+	if inviteErr != nil {
+		result.InviteOK = false
+		result.Message = fmt.Sprintf("兑换成功，但邀请发送失败: %v\n请联系管理员手动添加", inviteErr)
+	} else {
+		result.InviteOK = true
+		result.Message = "兑换成功！邀请邮件已发送到您的邮箱，请查收。"
+	}
+	return result, nil
+}
+
+// GenerateCode creates a random code in XXXX-XXXX-XXXX format.
+func GenerateCode() string {
+	parts := make([]byte, 12)
+	for i := range parts {
+		parts[i] = codeChars[rand.Intn(len(codeChars))]
+	}
+	return fmt.Sprintf("%s-%s-%s", string(parts[0:4]), string(parts[4:8]), string(parts[8:12]))
+}
+
+// GenerateCodes creates n unique codes.
+func GenerateCodes(n int) []string {
+	seen := make(map[string]bool)
+	var codes []string
+	for len(codes) < n {
+		c := GenerateCode()
+		if !seen[c] {
+			seen[c] = true
+			codes = append(codes, c)
+		}
+	}
+	return codes
+}
+
+// syncCounts updates user_count and invite_count from the ChatGPT API.
+func syncCounts(db *database.DB, client *chatgpt.Client, account *model.GptAccount) {
+	userTotal, _, err := client.GetUsers(account)
+	if err != nil {
+		return
+	}
+	inviteTotal, _, err := client.GetInvites(account)
+	if err != nil {
+		return
+	}
+	_ = db.UpdateAccountCounts(account.ID, userTotal, inviteTotal)
+}