Merge PR #73: feat(antigravity): 添加 Antigravity (Cloud AI Companion) 平台支持

新增功能:
- Antigravity OAuth 授权流程支持
- Claude → Gemini 协议转换（Claude API 请求自动转换为 Gemini 格式）
- 配额刷新和状态显示
- 混合调度功能，支持 Anthropic 和 Antigravity 账户混合使用
- /antigravity 专用路由，支持仅使用 Antigravity 账户
- 前端 Antigravity 服务商标识和账户管理功能

冲突解决:
- CreateAccountModal.vue: 合并 data-tour 属性和 mixed-scheduling 属性
- EditAccountModal.vue: 合并 data-tour 属性和 mixed-scheduling 属性

代码质量改进:
- 修复 antigravity 类型文件的 gofmt 格式问题（struct 字段对齐、interface{} → any）
- 移除 .golangci.yml 中的 gofmt 排除规则
- 修复测试文件的格式问题

backend/internal/repository/account_repo.go

@@ -337,6 +337,56 @@ func (r *accountRepository) ListSchedulableByGroupIDAndPlatform(ctx context.Cont
 	return outAccounts, nil
 }
 
+func (r *accountRepository) ListSchedulableByPlatforms(ctx context.Context, platforms []string) ([]service.Account, error) {
+	if len(platforms) == 0 {
+		return nil, nil
+	}
+	var accounts []accountModel
+	now := time.Now()
+	err := r.db.WithContext(ctx).
+		Where("platform IN ?", platforms).
+		Where("status = ? AND schedulable = ?", service.StatusActive, true).
+		Where("(overload_until IS NULL OR overload_until <= ?)", now).
+		Where("(rate_limit_reset_at IS NULL OR rate_limit_reset_at <= ?)", now).
+		Preload("Proxy").
+		Order("priority ASC").
+		Find(&accounts).Error
+	if err != nil {
+		return nil, err
+	}
+	outAccounts := make([]service.Account, 0, len(accounts))
+	for i := range accounts {
+		outAccounts = append(outAccounts, *accountModelToService(&accounts[i]))
+	}
+	return outAccounts, nil
+}
+
+func (r *accountRepository) ListSchedulableByGroupIDAndPlatforms(ctx context.Context, groupID int64, platforms []string) ([]service.Account, error) {
+	if len(platforms) == 0 {
+		return nil, nil
+	}
+	var accounts []accountModel
+	now := time.Now()
+	err := r.db.WithContext(ctx).
+		Joins("JOIN account_groups ON account_groups.account_id = accounts.id").
+		Where("account_groups.group_id = ?", groupID).
+		Where("accounts.platform IN ?", platforms).
+		Where("accounts.status = ? AND accounts.schedulable = ?", service.StatusActive, true).
+		Where("(accounts.overload_until IS NULL OR accounts.overload_until <= ?)", now).
+		Where("(accounts.rate_limit_reset_at IS NULL OR accounts.rate_limit_reset_at <= ?)", now).
+		Preload("Proxy").
+		Order("account_groups.priority ASC, accounts.priority ASC").
+		Find(&accounts).Error
+	if err != nil {
+		return nil, err
+	}
+	outAccounts := make([]service.Account, 0, len(accounts))
+	for i := range accounts {
+		outAccounts = append(outAccounts, *accountModelToService(&accounts[i]))
+	}
+	return outAccounts, nil
+}
+
 func (r *accountRepository) SetRateLimited(ctx context.Context, id int64, resetAt time.Time) error {
 	now := time.Now()
 	return r.db.WithContext(ctx).Model(&accountModel{}).Where("id = ?", id).