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/service/gateway_request_test.go

@@ -1,40 +1,40 @@
-package service
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/require"
-)
-
-func TestParseGatewayRequest(t *testing.T) {
-	body := []byte(`{"model":"claude-3-7-sonnet","stream":true,"metadata":{"user_id":"session_123e4567-e89b-12d3-a456-426614174000"},"system":[{"type":"text","text":"hello","cache_control":{"type":"ephemeral"}}],"messages":[{"content":"hi"}]}`)
-	parsed, err := ParseGatewayRequest(body)
-	require.NoError(t, err)
-	require.Equal(t, "claude-3-7-sonnet", parsed.Model)
-	require.True(t, parsed.Stream)
-	require.Equal(t, "session_123e4567-e89b-12d3-a456-426614174000", parsed.MetadataUserID)
-	require.True(t, parsed.HasSystem)
-	require.NotNil(t, parsed.System)
-	require.Len(t, parsed.Messages, 1)
-}
-
-func TestParseGatewayRequest_SystemNull(t *testing.T) {
-	body := []byte(`{"model":"claude-3","system":null}`)
-	parsed, err := ParseGatewayRequest(body)
-	require.NoError(t, err)
-	// 显式传入 system:null 也应视为“字段已存在”，避免默认 system 被注入。
-	require.True(t, parsed.HasSystem)
-	require.Nil(t, parsed.System)
-}
-
-func TestParseGatewayRequest_InvalidModelType(t *testing.T) {
-	body := []byte(`{"model":123}`)
-	_, err := ParseGatewayRequest(body)
-	require.Error(t, err)
-}
-
-func TestParseGatewayRequest_InvalidStreamType(t *testing.T) {
-	body := []byte(`{"stream":"true"}`)
-	_, err := ParseGatewayRequest(body)
-	require.Error(t, err)
-}
+package service
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestParseGatewayRequest(t *testing.T) {
+	body := []byte(`{"model":"claude-3-7-sonnet","stream":true,"metadata":{"user_id":"session_123e4567-e89b-12d3-a456-426614174000"},"system":[{"type":"text","text":"hello","cache_control":{"type":"ephemeral"}}],"messages":[{"content":"hi"}]}`)
+	parsed, err := ParseGatewayRequest(body)
+	require.NoError(t, err)
+	require.Equal(t, "claude-3-7-sonnet", parsed.Model)
+	require.True(t, parsed.Stream)
+	require.Equal(t, "session_123e4567-e89b-12d3-a456-426614174000", parsed.MetadataUserID)
+	require.True(t, parsed.HasSystem)
+	require.NotNil(t, parsed.System)
+	require.Len(t, parsed.Messages, 1)
+}
+
+func TestParseGatewayRequest_SystemNull(t *testing.T) {
+	body := []byte(`{"model":"claude-3","system":null}`)
+	parsed, err := ParseGatewayRequest(body)
+	require.NoError(t, err)
+	// 显式传入 system:null 也应视为“字段已存在”，避免默认 system 被注入。
+	require.True(t, parsed.HasSystem)
+	require.Nil(t, parsed.System)
+}
+
+func TestParseGatewayRequest_InvalidModelType(t *testing.T) {
+	body := []byte(`{"model":123}`)
+	_, err := ParseGatewayRequest(body)
+	require.Error(t, err)
+}
+
+func TestParseGatewayRequest_InvalidStreamType(t *testing.T) {
+	body := []byte(`{"stream":"true"}`)
+	_, err := ParseGatewayRequest(body)
+	require.Error(t, err)
+}