feat: add audit service and request context middleware

internal/audit/middleware.go

@@ -0,0 +1,30 @@
+package audit
+
+import (
+	"net"
+	"strings"
+
+	"github.com/gin-gonic/gin"
+	"mal/internal/auditctx"
+)
+
+func ContextMiddleware() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		ip := clientIP(c.ClientIP())
+		userAgent := strings.TrimSpace(c.GetHeader("User-Agent"))
+		c.Request = c.Request.WithContext(auditctx.WithRequestInfo(c.Request.Context(), ip, userAgent))
+		c.Next()
+	}
+}
+
+func clientIP(ip string) string {
+	trimmed := strings.TrimSpace(ip)
+	if trimmed == "" {
+		return ""
+	}
+	parsed := net.ParseIP(trimmed)
+	if parsed == nil {
+		return trimmed
+	}
+	return parsed.String()
+}