feat(server/auth): 新用户注册欢迎通知——注册同事务插 reward 类到账(零孤儿)

CreateUserWithTrial 新增本地 Noticer 接口(同 InsertNoticeTx 签名,参照 reward
包做法避免 notices→auth 循环依赖);SQLStore 加 noticer 字段 + SetNoticer,
nil-safe。注册事务插完 trial 订阅、commit 前,若已注入 noticer 则同事务插一条
type=reward 的双语欢迎通知(标题/正文按 trialDays 参数化),失败即整事务回滚,
与 reward/pay 到账钩子同语义、零孤儿。main.go 在 noticesStore 构造后装配
authStore.SetNoticer(noticesStore)(authStore 提升到 if-block 外声明以跨块可见)。

顺带修复 isDuplicateKey 只认 MySQL 错误文案的 dialect 缺口——sqlite 下重复邮箱
注册此前会落入错误分支返回不透明的「auth: insert user」,而非 ErrEmailTaken;
现同时匹配 sqlite 的 "UNIQUE constraint failed"。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P9G7E3wmAYL9KeYCVZVsqu

server/internal/auth/store.go

@@ -42,14 +42,25 @@ type UserStore interface {
 	GetUserByEmail(ctx context.Context, email string) (*User, error)
 }
 
+// Noticer 抽象 notices.Store 的事务内插入入口(测试可替身;生产传 notices.NewStore(db))。
+// auth → notices 单向依赖,不引入 import cycle,故本地声明接口、不直接 import notices
+// (参照 reward 包 Noticer 的做法)。
+type Noticer interface {
+	InsertNoticeTx(ctx context.Context, tx *sql.Tx, userID int64, typ, titleZH, titleEN, bodyZH, bodyEN, link string, now time.Time) error
+}
+
 // SQLStore is the MySQL-backed UserStore.
 type SQLStore struct {
-	db *sql.DB
+	db      *sql.DB
+	noticer Noticer
 }
 
 // NewSQLStore builds a SQLStore.
 func NewSQLStore(db *sql.DB) *SQLStore { return &SQLStore{db: db} }
 
+// SetNoticer 注入注册欢迎通知钩子(notices.Store 满足此接口);为 nil 时跳过(装配前兼容)。
+func (s *SQLStore) SetNoticer(n Noticer) { s.noticer = n }
+
 // CreateUserWithTrial implements UserStore.
 func (s *SQLStore) CreateUserWithTrial(ctx context.Context, email, pwHash string, trialDays int) (*User, error) {
 	userUUID := uuid.NewString()
@@ -95,6 +106,17 @@ func (s *SQLStore) CreateUserWithTrial(ctx context.Context, email, pwHash string
 		return nil, fmt.Errorf("auth: insert trial subscription: %w", err)
 	}
 
+	// 欢迎站内通知:同事务插入,注册回滚则通知不留(零孤儿),与 reward/pay 到账接缝同语义。
+	if s.noticer != nil {
+		titleZH := "欢迎加入 Pangolin 🎉"
+		titleEN := "Welcome to Pangolin 🎉"
+		bodyZH := fmt.Sprintf("已为你开通 %d 天 PRO 会员,现在就选节点连接,畅享全球网络。", trialDays)
+		bodyEN := fmt.Sprintf("Your %d-day PRO trial is active. Pick a node and connect to enjoy unrestricted access.", trialDays)
+		if err := s.noticer.InsertNoticeTx(ctx, tx, userID, "reward", titleZH, titleEN, bodyZH, bodyEN, "", now); err != nil {
+			return nil, fmt.Errorf("auth: insert welcome notice: %w", err)
+		}
+	}
+
 	if err := tx.Commit(); err != nil {
 		return nil, fmt.Errorf("auth: commit: %w", err)
 	}
@@ -125,11 +147,15 @@ func (s *SQLStore) GetUserByEmail(ctx context.Context, email string) (*User, err
 	return &u, nil
 }
 
-// isDuplicateKey reports whether err is a MySQL duplicate-key (1062) error.
+// isDuplicateKey reports whether err is a duplicate-key/unique-constraint
+// violation, dialect-neutral: MySQL ("Duplicate entry" / 1062) and sqlite
+// (modernc.org/sqlite "UNIQUE constraint failed" / SQLITE_CONSTRAINT_UNIQUE
+// 2067) both matched by message text.
 func isDuplicateKey(err error) bool {
 	if err == nil {
 		return false
 	}
 	msg := err.Error()
-	return strings.Contains(msg, "Duplicate entry") || strings.Contains(msg, "1062")
+	return strings.Contains(msg, "Duplicate entry") || strings.Contains(msg, "1062") ||
+		strings.Contains(msg, "UNIQUE constraint failed")
 }