merge: 合并main分支最新改动

解决冲突：
- backend/internal/config/config.go: 合并Ops和Dashboard配置
- backend/internal/server/api_contract_test.go: 合并handler初始化
- backend/internal/service/openai_gateway_service.go: 保留Ops错误追踪逻辑
- backend/internal/service/wire.go: 合并Ops和APIKeyAuth provider

主要合并内容：
- Dashboard缓存和预聚合功能
- API Key认证缓存优化
- Codex转换支持
- 使用日志分区表

backend/internal/handler/openai_gateway_handler.go

@@ -8,6 +8,7 @@ import (
 	"io"
 	"log"
 	"net/http"
+	"strings"
 	"time"
 
 	"github.com/Wei-Shaw/sub2api/internal/config"
@@ -94,15 +95,19 @@ func (h *OpenAIGatewayHandler) Responses(c *gin.Context) {
 		return
 	}
 
-	// For non-Codex CLI requests, set default instructions
 	userAgent := c.GetHeader("User-Agent")
 	if !openai.IsCodexCLIRequest(userAgent) {
-		reqBody["instructions"] = openai.DefaultInstructions
-		// Re-serialize body
-		body, err = json.Marshal(reqBody)
-		if err != nil {
-			h.errorResponse(c, http.StatusInternalServerError, "api_error", "Failed to process request")
-			return
+		existingInstructions, _ := reqBody["instructions"].(string)
+		if strings.TrimSpace(existingInstructions) == "" {
+			if instructions := strings.TrimSpace(service.GetOpenCodeInstructions()); instructions != "" {
+				reqBody["instructions"] = instructions
+				// Re-serialize body
+				body, err = json.Marshal(reqBody)
+				if err != nil {
+					h.errorResponse(c, http.StatusInternalServerError, "api_error", "Failed to process request")
+					return
+				}
+			}
 		}
 	}