新增 OIDC/SSO、邮件验证码与 Gitea 项目同步，并强化 Feed 与管理后台。

作为 OIDC Provider 对接 Gitea；注册支持邮件验证码/验证码；侧栏同步公开仓库；Feed 分页、文章大纲、标签云与站点品牌设置。

Co-authored-by: Cursor <cursoragent@cursor.com>

service/email_code.go

@@ -0,0 +1,128 @@
+package service
+
+import (
+	"crypto/rand"
+	"fmt"
+	"math/big"
+	"strings"
+	"sync"
+	"time"
+
+	"git.iioio.com/freefire/jiang13-forum/model"
+)
+
+const (
+	emailCodeLen      = 6
+	emailCodeTTL      = 10 * time.Minute
+	emailCodeCooldown = 60 * time.Second
+)
+
+type emailCodeEntry struct {
+	code      string
+	expiresAt time.Time
+	sentAt    time.Time
+}
+
+// EmailCodeService 注册邮箱验证码
+type EmailCodeService struct {
+	mu      sync.Mutex
+	entries map[string]emailCodeEntry
+	mail    *MailService
+}
+
+func NewEmailCodeService(mail *MailService) *EmailCodeService {
+	s := &EmailCodeService{
+		entries: make(map[string]emailCodeEntry),
+		mail:    mail,
+	}
+	go s.cleanup()
+	return s
+}
+
+// SendRegisterCode 向邮箱发送注册验证码
+func (s *EmailCodeService) SendRegisterCode(email string) error {
+	email = NormalizeEmail(email)
+	if err := ValidateEmail(email); err != nil {
+		return err
+	}
+
+	var exist model.User
+	if err := model.DB.Where("email = ?", email).First(&exist).Error; err == nil {
+		return ErrEmailExists
+	}
+
+	s.mu.Lock()
+	if prev, ok := s.entries[email]; ok && time.Since(prev.sentAt) < emailCodeCooldown {
+		s.mu.Unlock()
+		return ErrEmailCodeCooldown
+	}
+	s.mu.Unlock()
+
+	code, err := randomDigits(emailCodeLen)
+	if err != nil {
+		return err
+	}
+
+	subject := "注册验证码"
+	body := fmt.Sprintf("您的注册验证码是：%s\n\n%d 分钟内有效，如非本人操作请忽略。", code, int(emailCodeTTL.Minutes()))
+	if err := s.mail.Send(email, subject, body); err != nil {
+		return err
+	}
+
+	s.mu.Lock()
+	s.entries[email] = emailCodeEntry{
+		code:      code,
+		expiresAt: time.Now().Add(emailCodeTTL),
+		sentAt:    time.Now(),
+	}
+	s.mu.Unlock()
+	return nil
+}
+
+// Verify 校验邮箱验证码（一次性）
+func (s *EmailCodeService) Verify(email, code string) bool {
+	email = NormalizeEmail(email)
+	code = strings.TrimSpace(code)
+	if email == "" || code == "" {
+		return false
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	entry, ok := s.entries[email]
+	if !ok {
+		return false
+	}
+	delete(s.entries, email)
+	if time.Now().After(entry.expiresAt) {
+		return false
+	}
+	return entry.code == code
+}
+
+func (s *EmailCodeService) cleanup() {
+	ticker := time.NewTicker(time.Minute)
+	for range ticker.C {
+		now := time.Now()
+		s.mu.Lock()
+		for email, entry := range s.entries {
+			if now.After(entry.expiresAt) {
+				delete(s.entries, email)
+			}
+		}
+		s.mu.Unlock()
+	}
+}
+
+func randomDigits(n int) (string, error) {
+	var b strings.Builder
+	b.Grow(n)
+	max := big.NewInt(10)
+	for i := 0; i < n; i++ {
+		v, err := rand.Int(rand.Reader, max)
+		if err != nil {
+			return "", err
+		}
+		b.WriteByte(byte('0' + v.Int64()))
+	}
+	return b.String(), nil
+}