Refactor email fetching logic in EmailController

Consolidated email fetching endpoints by removing `FetchEmailUids`
and `FetchEmailByUid` endpoints and integrating their functionality
into the `FetchEmails` method. Introduced an `OnlyFilter` enum to
allow filtering responses for HTML body or UIDs. Removed related
methods (`FetchEmailUidsAsync`, `FetchEmailByUidAsync`) from
`IImapEmailService` and deleted associated query classes and
handlers.

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

@@ -22,27 +22,6 @@ public interface IImapEmailService
         MailSearchFilter filter,
         CancellationToken cancellationToken = default);
 
-    /// <summary>
-    /// Fetches only the UIDs of messages matching the specified filter.
-    /// </summary>
-    Task<IEnumerable<long>> FetchEmailUidsAsync(
-        EmailAccountDto account,
-        MailSearchFilter filter,
-        CancellationToken cancellationToken = default);
-
-    /// <summary>
-    /// Fetches a single email by its UID.
-    /// </summary>
-    /// When <see langword="true"/> (default), the message is marked as <c>\Seen</c> on the server.
-    /// Set to <see langword="false"/> for a non-destructive read.
-    /// </param>
-    Task<ReceivedEmailContext?> FetchEmailByUidAsync(
-        EmailAccountDto account,
-        long uid,
-        string folder = "INBOX",
-        bool withAttachments = false,
-        CancellationToken cancellationToken = default);
-
     /// <summary>
     /// Marks a message as seen (read) on the server.
     /// </summary>