feat(billing): 统一计价与候选冻结估算

新增 effective-pricing-v2、9 位十进制定点计算、显式免费校验和结构化缺价错误。估价与生产预处理覆盖全部可用候选，并按最大候选费用冻结；规则优先级为平台模型、平台、基准模型。\n\n同步计价契约和 OpenAPI，补充 Token 参数别名、视频五秒向上取整及缺价回归测试。\n\n验证：go test ./...、pnpm openapi、Web 测试与构建通过。

apps/api/internal/httpapi/pricing_handlers.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"net/http"
 	"strings"
+	"time"
 
 	"github.com/easyai/easyai-ai-gateway/apps/api/internal/store"
 )
@@ -146,10 +147,38 @@ func validPricingRuleSetInput(input store.PricingRuleSetInput) bool {
 	if strings.TrimSpace(input.RuleSetKey) == "" || strings.TrimSpace(input.Name) == "" || len(input.Rules) == 0 {
 		return false
 	}
+	if currency := strings.TrimSpace(input.Currency); currency != "" && currency != "resource" {
+		return false
+	}
 	for _, rule := range input.Rules {
 		if strings.TrimSpace(rule.ResourceType) == "" || strings.TrimSpace(rule.Unit) == "" {
 			return false
 		}
+		if rule.BasePrice < 0 || (rule.BasePrice == 0 && !rule.IsFree) {
+			return false
+		}
+		if currency := strings.TrimSpace(rule.Currency); currency != "" && currency != "resource" {
+			return false
+		}
+		switch calculator := strings.TrimSpace(rule.CalculatorType); calculator {
+		case "", "token_usage", "unit_weight", "duration_weight":
+		default:
+			return false
+		}
+		effectiveFrom, fromOK := pricingEffectiveTime(rule.EffectiveFrom)
+		effectiveTo, toOK := pricingEffectiveTime(rule.EffectiveTo)
+		if !fromOK || !toOK || (!effectiveFrom.IsZero() && !effectiveTo.IsZero() && !effectiveFrom.Before(effectiveTo)) {
+			return false
+		}
 	}
 	return true
 }
+
+func pricingEffectiveTime(value string) (time.Time, bool) {
+	value = strings.TrimSpace(value)
+	if value == "" {
+		return time.Time{}, true
+	}
+	parsed, err := time.Parse(time.RFC3339, value)
+	return parsed, err == nil
+}