refactor(startup): migrate from generic Host to WebApplication and integrate Web API support

- Replaced Host.CreateApplicationBuilder with WebApplication.CreateBuilder
- Added Web API service registrations (Controllers, Swagger)
- Organized startup into clear regions: Logging, Configuration, Worker, Services, Middleware
- Introduced Swagger and HTTPS middleware for API
- Improved structure and readability of Program.cs

EnvelopeGenerator.Finalizer/Properties/launchSettings.json

@@ -1,12 +1,41 @@
 {
   "$schema": "http://json.schemastore.org/launchsettings.json",
+  "iisSettings": {
+    "windowsAuthentication": false,
+    "anonymousAuthentication": true,
+    "iisExpress": {
+      "applicationUrl": "http://localhost:17119",
+      "sslPort": 44321
+    }
+  },
   "profiles": {
-    "EnvelopeGenerator.Finalizer": {
+    "http": {
       "commandName": "Project",
       "dotnetRunMessages": true,
+      "launchBrowser": false,
+      "launchUrl": "swagger",
+      "applicationUrl": "http://localhost:5010",
       "environmentVariables": {
-        "DOTNET_ENVIRONMENT": "Development"
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    },
+    "https": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": false,
+      "launchUrl": "swagger",
+      "applicationUrl": "https://localhost:7141;http://localhost:5010",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    },
+    "IIS Express": {
+      "commandName": "IISExpress",
+      "launchBrowser": false,
+      "launchUrl": "swagger",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
       }
     }
   }
-}
+}