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/gemini_oauth_service_test.go

@@ -1,51 +1,51 @@
-package service
-
-import "testing"
-
-func TestInferGoogleOneTier(t *testing.T) {
-	tests := []struct {
-		name         string
-		storageBytes int64
-		expectedTier string
-	}{
-		{"Negative storage", -1, TierGoogleOneUnknown},
-		{"Zero storage", 0, TierGoogleOneUnknown},
-
-		// Free tier boundary (15GB)
-		{"Below free tier", 10 * GB, TierGoogleOneUnknown},
-		{"Just below free tier", StorageTierFree - 1, TierGoogleOneUnknown},
-		{"Free tier (15GB)", StorageTierFree, TierFree},
-
-		// Basic tier boundary (100GB)
-		{"Between free and basic", 50 * GB, TierFree},
-		{"Just below basic tier", StorageTierBasic - 1, TierFree},
-		{"Basic tier (100GB)", StorageTierBasic, TierGoogleOneBasic},
-
-		// Standard tier boundary (200GB)
-		{"Between basic and standard", 150 * GB, TierGoogleOneBasic},
-		{"Just below standard tier", StorageTierStandard - 1, TierGoogleOneBasic},
-		{"Standard tier (200GB)", StorageTierStandard, TierGoogleOneStandard},
-
-		// AI Premium tier boundary (2TB)
-		{"Between standard and premium", 1 * TB, TierGoogleOneStandard},
-		{"Just below AI Premium tier", StorageTierAIPremium - 1, TierGoogleOneStandard},
-		{"AI Premium tier (2TB)", StorageTierAIPremium, TierAIPremium},
-
-		// Unlimited tier boundary (> 100TB)
-		{"Between premium and unlimited", 50 * TB, TierAIPremium},
-		{"At unlimited threshold (100TB)", StorageTierUnlimited, TierAIPremium},
-		{"Unlimited tier (100TB+)", StorageTierUnlimited + 1, TierGoogleOneUnlimited},
-		{"Unlimited tier (101TB+)", 101 * TB, TierGoogleOneUnlimited},
-		{"Very large storage", 1000 * TB, TierGoogleOneUnlimited},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			result := inferGoogleOneTier(tt.storageBytes)
-			if result != tt.expectedTier {
-				t.Errorf("inferGoogleOneTier(%d) = %s, want %s",
-					tt.storageBytes, result, tt.expectedTier)
-			}
-		})
-	}
-}
+package service
+
+import "testing"
+
+func TestInferGoogleOneTier(t *testing.T) {
+	tests := []struct {
+		name         string
+		storageBytes int64
+		expectedTier string
+	}{
+		{"Negative storage", -1, TierGoogleOneUnknown},
+		{"Zero storage", 0, TierGoogleOneUnknown},
+
+		// Free tier boundary (15GB)
+		{"Below free tier", 10 * GB, TierGoogleOneUnknown},
+		{"Just below free tier", StorageTierFree - 1, TierGoogleOneUnknown},
+		{"Free tier (15GB)", StorageTierFree, TierFree},
+
+		// Basic tier boundary (100GB)
+		{"Between free and basic", 50 * GB, TierFree},
+		{"Just below basic tier", StorageTierBasic - 1, TierFree},
+		{"Basic tier (100GB)", StorageTierBasic, TierGoogleOneBasic},
+
+		// Standard tier boundary (200GB)
+		{"Between basic and standard", 150 * GB, TierGoogleOneBasic},
+		{"Just below standard tier", StorageTierStandard - 1, TierGoogleOneBasic},
+		{"Standard tier (200GB)", StorageTierStandard, TierGoogleOneStandard},
+
+		// AI Premium tier boundary (2TB)
+		{"Between standard and premium", 1 * TB, TierGoogleOneStandard},
+		{"Just below AI Premium tier", StorageTierAIPremium - 1, TierGoogleOneStandard},
+		{"AI Premium tier (2TB)", StorageTierAIPremium, TierAIPremium},
+
+		// Unlimited tier boundary (> 100TB)
+		{"Between premium and unlimited", 50 * TB, TierAIPremium},
+		{"At unlimited threshold (100TB)", StorageTierUnlimited, TierAIPremium},
+		{"Unlimited tier (100TB+)", StorageTierUnlimited + 1, TierGoogleOneUnlimited},
+		{"Unlimited tier (101TB+)", 101 * TB, TierGoogleOneUnlimited},
+		{"Very large storage", 1000 * TB, TierGoogleOneUnlimited},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := inferGoogleOneTier(tt.storageBytes)
+			if result != tt.expectedTier {
+				t.Errorf("inferGoogleOneTier(%d) = %s, want %s",
+					tt.storageBytes, result, tt.expectedTier)
+			}
+		})
+	}
+}