Add receiver management to EnvelopeSenderEditorPage

Introduced a new "Receivers" panel in `EnvelopeSenderEditorPage` to manage receivers. Added a popup for adding receivers with validation, email suggestions, and caching for performance. Updated the layout to display receiver details and signature fields.

Injected `EnvelopeReceiverPageDataService` for receiver-related operations. Added a `ReceiverDraft` model and implemented methods for managing receivers. Enhanced CSS for the new UI elements and ensured responsiveness. Minor refactoring and cleanup included.

EnvelopeGenerator.Server/EnvelopeGenerator.Server/Services/EnvelopeReceiverPageDataService.cs

@@ -4,12 +4,14 @@ using EnvelopeGenerator.Application.Common.Dto;
 using EnvelopeGenerator.Application.Common.Dto.EnvelopeReceiver;
 using EnvelopeGenerator.Application.Documents.Queries;
 using EnvelopeGenerator.Application.EnvelopeReceivers.Queries;
+using EnvelopeGenerator.Application.Receivers.Queries;
 using EnvelopeGenerator.Server.Client.Models;
 using EnvelopeGenerator.Server.Client.Models.Constants;
 using EnvelopeGenerator.Server.Extensions;
 using EnvelopeGenerator.Server.Options;
 using MediatR;
 using Microsoft.Extensions.Caching.Distributed;
+using Microsoft.Extensions.Caching.Memory;
 using Microsoft.Extensions.Options;
 using ApplicationEnvelopeReceiverDto = EnvelopeGenerator.Application.Common.Dto.EnvelopeReceiver.EnvelopeReceiverDto;
 
@@ -21,7 +23,8 @@ namespace EnvelopeGenerator.Server.Services;
 public class EnvelopeReceiverPageDataService(
     IMediator mediator,
     IDistributedCache cache,
-    IOptions<CacheOptions> cacheOptions)
+    IOptions<CacheOptions> cacheOptions,
+    IMemoryCache memoryCache)
 {
     private const string SignatureCacheKeyPrefix = "envelope-generator.receiver-ui.signature:";
 
@@ -101,4 +104,23 @@ public class EnvelopeReceiverPageDataService(
         Page = element.Page,
         SenderAppType = (EnvelopeGenerator.Server.Client.Models.Constants.SenderAppType)element.SenderAppType
     };
+
+    private static readonly string ReceiverEmailSearchCacheKey = Guid.NewGuid().ToString();
+
+    public async Task<IEnumerable<string>> SearchReceiverEMailsAsync(string emailSearchTerm, CancellationToken cancellationToken = default)
+    {
+
+        return await memoryCache.GetOrCreateAsync(ReceiverEmailSearchCacheKey + emailSearchTerm, async entry =>
+        {
+            var query = new ReadReceiverQuery { EmailAddressSearch = emailSearchTerm };
+            var receivers = await mediator.Send(query, cancellationToken);
+
+            if(receivers.Any())
+                entry.AbsoluteExpirationRelativeToNow = TimeSpan.FromSeconds(30);
+            else
+                entry.AbsoluteExpirationRelativeToNow = TimeSpan.FromSeconds(10);
+
+            return receivers.Select(r => r.EmailAddress);
+        }) ?? [];
+    }
 }