Add NLog file logging configuration and error handling

Integrate NLog for structured file-based logging by adding configuration to appsettings.json and initializing NLog in Program.cs. Wrap application startup in a try-catch block to log unhandled exceptions. No changes to core application logic.

Program.cs

@@ -1,6 +1,13 @@
 using Microsoft.AspNetCore.Authentication.Negotiate;
 using Microsoft.OpenApi.Models;
+using NLog;
+using NLog.Web;
 
+var logger = LogManager.Setup().LoadConfigurationFromAppSettings().GetCurrentClassLogger();
+logger.Info("Logging initialized!");
+
+try
+{
     var builder = WebApplication.CreateBuilder(args);
 
 
@@ -70,3 +77,9 @@ app.UseAuthorization();
     app.MapControllers();
 
     app.Run();
+}
+catch (Exception ex)
+{
+    logger.Error(ex, "Stopped program because of exception");
+    throw;
+}

appsettings.json

@@ -11,5 +11,48 @@
       "Protocols": "Http1"
     }
   },
-  "EnableSwagger": true
+  "EnableSwagger": true,
+  "NLog": {
+    "throwConfigExceptions": true,
+    "variables": {
+      "logDirectory": "E:\\LogFiles\\Digital Data\\FakeNTLMServer",
+      "logFileNamePrefix": "${shortdate}-FakeNTLMServer"
+    },
+    "targets": {
+      "infoLogs": {
+        "type": "File",
+        "fileName": "${logDirectory}\\${logFileNamePrefix}-Info.log",
+        "maxArchiveDays": 30
+      },
+      "errorLogs": {
+        "type": "File",
+        "fileName": "${logDirectory}\\${logFileNamePrefix}-Error.log",
+        "maxArchiveDays": 30
+      },
+      "criticalLogs": {
+        "type": "File",
+        "fileName": "${logDirectory}\\${logFileNamePrefix}-Critical.log",
+        "maxArchiveDays": 30
+      }
+    },
+    // Trace, Debug, Info, Warn, Error and *Fatal*
+    "rules": [
+      {
+        "logger": "*",
+        "minLevel": "Info",
+        "maxLevel": "Warn",
+        "writeTo": "infoLogs"
+      },
+      {
+        "logger": "*",
+        "level": "Error",
+        "writeTo": "errorLogs"
+      },
+      {
+        "logger": "*",
+        "level": "Fatal",
+        "writeTo": "criticalLogs"
+      }
+    ]
+  }
 }