fix(ops): 修复日志级别过滤并增强OpenAI错误诊断日志

- 移除 warn 级别下 access info 的强制入库补写，确保运行时日志级别真实生效

- 将 OpenAI fallback matched 与 passthrough 断流提示按需求降级为 info

- 为 codex_cli_only 与 instructions required 场景补充请求诊断字段（含 User-Agent）

- 出于安全考虑移除请求体预览，仅保留 request_body_size 与白名单头信息

- 新增/更新回归测试，覆盖 Forward 入口到日志落库链路

backend/internal/service/pricing_service.go

@@ -17,6 +17,7 @@ import (
 	"github.com/Wei-Shaw/sub2api/internal/pkg/logger"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/openai"
 	"github.com/Wei-Shaw/sub2api/internal/util/urlvalidator"
+	"go.uber.org/zap"
 )
 
 var (
@@ -659,7 +660,8 @@ func (s *PricingService) matchOpenAIModel(model string) *LiteLLMModelPricing {
 	if strings.HasPrefix(model, "gpt-5.3-codex-spark") {
 		if pricing, ok := s.pricingData["gpt-5.1-codex"]; ok {
 			logger.LegacyPrintf("service.pricing", "[Pricing][SparkBilling] %s -> %s billing", model, "gpt-5.1-codex")
-			logger.LegacyPrintf("service.pricing", "[Pricing] OpenAI fallback matched %s -> %s", model, "gpt-5.1-codex")
+			logger.With(zap.String("component", "service.pricing")).
+				Info(fmt.Sprintf("[Pricing] OpenAI fallback matched %s -> %s", model, "gpt-5.1-codex"))
 			return pricing
 		}
 	}
@@ -669,14 +671,16 @@ func (s *PricingService) matchOpenAIModel(model string) *LiteLLMModelPricing {
 
 	for _, variant := range variants {
 		if pricing, ok := s.pricingData[variant]; ok {
-			logger.LegacyPrintf("service.pricing", "[Pricing] OpenAI fallback matched %s -> %s", model, variant)
+			logger.With(zap.String("component", "service.pricing")).
+				Info(fmt.Sprintf("[Pricing] OpenAI fallback matched %s -> %s", model, variant))
 			return pricing
 		}
 	}
 
 	if strings.HasPrefix(model, "gpt-5.3-codex") {
 		if pricing, ok := s.pricingData["gpt-5.2-codex"]; ok {
-			logger.LegacyPrintf("service.pricing", "[Pricing] OpenAI fallback matched %s -> %s", model, "gpt-5.2-codex")
+			logger.With(zap.String("component", "service.pricing")).
+				Info(fmt.Sprintf("[Pricing] OpenAI fallback matched %s -> %s", model, "gpt-5.2-codex"))
 			return pricing
 		}
 	}