Refactor IMAP service for repository integration

Replaced `FetchEmailsAsync` with `SyncEmailsAsync` in `IImapEmailService` to simplify email synchronization. Updated method signatures to use `DateFilter` and added default parameters for `folder` and `cancel`.

Refactored `LimilabsImapEmailService` to remove client-side filtering logic and delegate storage to `IRepository<ReceivedEmail>`. Simplified IMAP search criteria to focus on date-based filtering and added checks to skip already-synced emails.

Updated `EmailSyncWorker` to use the new `SyncEmailsAsync` method. Removed unused code, streamlined exception handling, and improved maintainability by reducing complexity and focusing on server-side filtering.

src/core/DigitalData.MessagingService.Application/Common/Interfaces/IImapEmailService.cs

@@ -14,15 +14,16 @@ public interface IImapEmailService
     /// Fetches emails from the specified mailbox folder.
     /// </summary>
     /// <param name="account">Account whose IMAP settings will be used.</param>
-    /// <param name="filter">Filter to apply when fetching emails.</param>
+    /// <param name="date"></param>
     /// When <see langword="true"/> (default), fetched messages are marked as <c>\Seen</c> on the server.
     /// Set to <see langword="false"/> for a non-destructive read (uses <c>BODY.PEEK</c> internally).
     /// </param>
     /// <param name="cancellationToken">Cancellation token.</param>
-    Task<IEnumerable<ReceivedEmailDto>> FetchEmailsAsync(
+    public Task SyncEmailsAsync(
         EmailAccount account,
-        MailSearchFilter filter,
-        CancellationToken cancellationToken = default);
+        DateFilter date,
+        string folder = "INBOX",
+        CancellationToken cancel = default);
 
     /// <summary>
     /// Marks a message as seen (read) on the server.