feat: 品牌重命名 Sub2API -> TianShuAPI

- 前端: 所有界面显示、i18n 文本、组件中的品牌名称
- 后端: 服务层、设置默认值、邮件模板、安装向导
- 数据库: 迁移脚本注释
- 保持功能完全一致，仅更改品牌名称

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

backend/internal/repository/email_cache.go

@@ -1,52 +1,52 @@
-package repository
-
-import (
-	"context"
-	"encoding/json"
-	"time"
-
-	"github.com/Wei-Shaw/sub2api/internal/service"
-	"github.com/redis/go-redis/v9"
-)
-
-const verifyCodeKeyPrefix = "verify_code:"
-
-// verifyCodeKey generates the Redis key for email verification code.
-func verifyCodeKey(email string) string {
-	return verifyCodeKeyPrefix + email
-}
-
-type emailCache struct {
-	rdb *redis.Client
-}
-
-func NewEmailCache(rdb *redis.Client) service.EmailCache {
-	return &emailCache{rdb: rdb}
-}
-
-func (c *emailCache) GetVerificationCode(ctx context.Context, email string) (*service.VerificationCodeData, error) {
-	key := verifyCodeKey(email)
-	val, err := c.rdb.Get(ctx, key).Result()
-	if err != nil {
-		return nil, err
-	}
-	var data service.VerificationCodeData
-	if err := json.Unmarshal([]byte(val), &data); err != nil {
-		return nil, err
-	}
-	return &data, nil
-}
-
-func (c *emailCache) SetVerificationCode(ctx context.Context, email string, data *service.VerificationCodeData, ttl time.Duration) error {
-	key := verifyCodeKey(email)
-	val, err := json.Marshal(data)
-	if err != nil {
-		return err
-	}
-	return c.rdb.Set(ctx, key, val, ttl).Err()
-}
-
-func (c *emailCache) DeleteVerificationCode(ctx context.Context, email string) error {
-	key := verifyCodeKey(email)
-	return c.rdb.Del(ctx, key).Err()
-}
+package repository
+
+import (
+	"context"
+	"encoding/json"
+	"time"
+
+	"github.com/Wei-Shaw/sub2api/internal/service"
+	"github.com/redis/go-redis/v9"
+)
+
+const verifyCodeKeyPrefix = "verify_code:"
+
+// verifyCodeKey generates the Redis key for email verification code.
+func verifyCodeKey(email string) string {
+	return verifyCodeKeyPrefix + email
+}
+
+type emailCache struct {
+	rdb *redis.Client
+}
+
+func NewEmailCache(rdb *redis.Client) service.EmailCache {
+	return &emailCache{rdb: rdb}
+}
+
+func (c *emailCache) GetVerificationCode(ctx context.Context, email string) (*service.VerificationCodeData, error) {
+	key := verifyCodeKey(email)
+	val, err := c.rdb.Get(ctx, key).Result()
+	if err != nil {
+		return nil, err
+	}
+	var data service.VerificationCodeData
+	if err := json.Unmarshal([]byte(val), &data); err != nil {
+		return nil, err
+	}
+	return &data, nil
+}
+
+func (c *emailCache) SetVerificationCode(ctx context.Context, email string, data *service.VerificationCodeData, ttl time.Duration) error {
+	key := verifyCodeKey(email)
+	val, err := json.Marshal(data)
+	if err != nil {
+		return err
+	}
+	return c.rdb.Set(ctx, key, val, ttl).Err()
+}
+
+func (c *emailCache) DeleteVerificationCode(ctx context.Context, email string) error {
+	key := verifyCodeKey(email)
+	return c.rdb.Del(ctx, key).Err()
+}