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/identity_cache.go

@@ -1,51 +1,51 @@
-package repository
-
-import (
-	"context"
-	"encoding/json"
-	"fmt"
-	"time"
-
-	"github.com/Wei-Shaw/sub2api/internal/service"
-	"github.com/redis/go-redis/v9"
-)
-
-const (
-	fingerprintKeyPrefix = "fingerprint:"
-	fingerprintTTL       = 24 * time.Hour
-)
-
-// fingerprintKey generates the Redis key for account fingerprint cache.
-func fingerprintKey(accountID int64) string {
-	return fmt.Sprintf("%s%d", fingerprintKeyPrefix, accountID)
-}
-
-type identityCache struct {
-	rdb *redis.Client
-}
-
-func NewIdentityCache(rdb *redis.Client) service.IdentityCache {
-	return &identityCache{rdb: rdb}
-}
-
-func (c *identityCache) GetFingerprint(ctx context.Context, accountID int64) (*service.Fingerprint, error) {
-	key := fingerprintKey(accountID)
-	val, err := c.rdb.Get(ctx, key).Result()
-	if err != nil {
-		return nil, err
-	}
-	var fp service.Fingerprint
-	if err := json.Unmarshal([]byte(val), &fp); err != nil {
-		return nil, err
-	}
-	return &fp, nil
-}
-
-func (c *identityCache) SetFingerprint(ctx context.Context, accountID int64, fp *service.Fingerprint) error {
-	key := fingerprintKey(accountID)
-	val, err := json.Marshal(fp)
-	if err != nil {
-		return err
-	}
-	return c.rdb.Set(ctx, key, val, fingerprintTTL).Err()
-}
+package repository
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"github.com/Wei-Shaw/sub2api/internal/service"
+	"github.com/redis/go-redis/v9"
+)
+
+const (
+	fingerprintKeyPrefix = "fingerprint:"
+	fingerprintTTL       = 24 * time.Hour
+)
+
+// fingerprintKey generates the Redis key for account fingerprint cache.
+func fingerprintKey(accountID int64) string {
+	return fmt.Sprintf("%s%d", fingerprintKeyPrefix, accountID)
+}
+
+type identityCache struct {
+	rdb *redis.Client
+}
+
+func NewIdentityCache(rdb *redis.Client) service.IdentityCache {
+	return &identityCache{rdb: rdb}
+}
+
+func (c *identityCache) GetFingerprint(ctx context.Context, accountID int64) (*service.Fingerprint, error) {
+	key := fingerprintKey(accountID)
+	val, err := c.rdb.Get(ctx, key).Result()
+	if err != nil {
+		return nil, err
+	}
+	var fp service.Fingerprint
+	if err := json.Unmarshal([]byte(val), &fp); err != nil {
+		return nil, err
+	}
+	return &fp, nil
+}
+
+func (c *identityCache) SetFingerprint(ctx context.Context, accountID int64, fp *service.Fingerprint) error {
+	key := fingerprintKey(accountID)
+	val, err := json.Marshal(fp)
+	if err != nil {
+		return err
+	}
+	return c.rdb.Set(ctx, key, val, fingerprintTTL).Err()
+}