Rename "Moonglade" to "Elf" in WebApplicationExtensions

Updated terminology from "Moonglade" to "Elf" in the
WebApplicationExtensions class. This includes changes to the
message in the Prevent method and the warning log for the
development environment check, addressing legal and regulatory
concerns in China.

Author: EdiWang

src/API/WebApplicationExtensions.cs

@@ -22,15 +22,15 @@ void Prevent()
             app.Logger.LogError("Positive China detection, application stopped.");
 
             app.MapGet("/", () => Results.Text(
-                "Due to legal and regulation concerns, we regret to inform you that deploying Moonglade on servers located in China (including Hong Kong) is currently not possible",
+                "Due to legal and regulation concerns, we regret to inform you that deploying Elf on servers located in China (including Hong Kong) is currently not possible",
                 statusCode: 251
             ));
             app.Run();
         }
 
         if (app.Environment.IsDevelopment())
         {
-            app.Logger.LogWarning("Current deployment is suspected to be located in China, Moonglade will still run on full functionality in development environment.");
+            app.Logger.LogWarning("Current deployment is suspected to be located in China, Elf will still run on full functionality in development environment.");
         }
         else
         {