Add NETFRAMEWORK-specific usings to API files

Added conditional using directives for System.Net.Http, System.Threading, and System.Threading.Tasks in multiple API files. These usings are now included only when targeting .NET Framework, improving compatibility and preventing unnecessary imports on other platforms.

src/ReC.Client/Api/CommonApi.cs

@@ -1,6 +1,8 @@
+#if NETFRAMEWORK
 using System.Net.Http;
 using System.Threading;
 using System.Threading.Tasks;
+#endif
 
 namespace ReC.Client.Api
 {

src/ReC.Client/Api/EndpointAuthApi.cs

@@ -1,6 +1,8 @@
+#if NETFRAMEWORK
 using System.Net.Http;
 using System.Threading;
 using System.Threading.Tasks;
+#endif
 
 namespace ReC.Client.Api
 {

src/ReC.Client/Api/EndpointParamsApi.cs

@@ -1,6 +1,8 @@
+#if NETFRAMEWORK
 using System.Net.Http;
 using System.Threading;
 using System.Threading.Tasks;
+#endif
 
 namespace ReC.Client.Api
 {

src/ReC.Client/Api/EndpointsApi.cs

@@ -1,6 +1,8 @@
+#if NETFRAMEWORK
 using System.Net.Http;
 using System.Threading;
 using System.Threading.Tasks;
+#endif
 
 namespace ReC.Client.Api
 {

src/ReC.Client/Api/ProfileApi.cs

@@ -1,6 +1,8 @@
+#if NETFRAMEWORK
 using System.Net.Http;
 using System.Threading;
 using System.Threading.Tasks;
+#endif
 
 namespace ReC.Client.Api
 {

src/ReC.Client/Api/RecActionApi.cs

@@ -1,6 +1,8 @@
+#if NETFRAMEWORK
 using System.Net.Http;
 using System.Threading;
 using System.Threading.Tasks;
+#endif
 
 namespace ReC.Client.Api
 {

src/ReC.Client/Api/ResultApi.cs

@@ -1,6 +1,8 @@
+#if NETFRAMEWORK
 using System.Net.Http;
 using System.Threading;
 using System.Threading.Tasks;
+#endif
 
 namespace ReC.Client.Api
 {