Refactor to use IHttpClientFactory and remove ApiOptions

Replaced direct injection of HttpClient with IHttpClientFactory
across the codebase to improve HTTP client management and align
with best practices. Removed dependency on ApiOptions and
IOptions<ApiOptions> in multiple services, simplifying constructors
and reducing configuration complexity.

Updated FontLoader to use IHttpClientFactory for font loading
with relative paths. Adjusted comments and documentation to
reflect these changes. Cleaned up unused using directives
related to ApiOptions.

EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Layout/MainLayout.razor

@@ -15,13 +15,14 @@
 </div>
 
 @code {
-    [Inject] HttpClient Http { get; set; }
+    [Inject] IHttpClientFactory HttpClientFactory { get; set; } = default!;
+    
     List<string> RequiredFonts = new() {
         "opensans.ttf"
     };
 
     protected async override Task OnInitializedAsync() {
-        await FontLoader.LoadFonts(Http, RequiredFonts);
+        await FontLoader.LoadFonts(HttpClientFactory, RequiredFonts);
         await base.OnInitializedAsync();
     }
 }