feat(email): add delivery adapters

Gmail and Graph request explicit send consent and classify provider rejection separately from uncertain transport failure. IMAP remains read-only; no send API is exposed.

JobTrackerApi/Services/EmailProviders/GmailProvider.cs

@@ -21,7 +21,7 @@ namespace JobTrackerApi.Services.EmailProviders
         public async Task<EmailConnectionInfo?> GetConnectionAsync(string ownerUserId, CancellationToken cancellationToken)
         {
             var connection = await _gmail.GetConnectionAsync(ownerUserId, cancellationToken);
-            return connection is null ? null : new EmailConnectionInfo("gmail", connection.GmailAddress ?? "");
+            return connection is null ? null : new EmailConnectionInfo("gmail", connection.GmailAddress ?? "", GmailOAuthService.HasSendScope(connection.Scope));
         }
 
         public async Task<IReadOnlyList<EmailMessageSummary>> SearchAsync(string ownerUserId, string? query, int maxResults, CancellationToken cancellationToken)
@@ -57,6 +57,12 @@ namespace JobTrackerApi.Services.EmailProviders
                 attachments);
         }
 
+        public async Task<EmailDeliveryResult> SendAsync(string ownerUserId, EmailDeliveryRequest request, CancellationToken cancellationToken)
+        {
+            var result = await _gmail.SendAsync(ownerUserId, new GmailSendRequest(request.To, request.Subject, request.BodyText, request.ThreadId), cancellationToken);
+            return new EmailDeliveryResult(result.MessageId, result.ThreadId);
+        }
+
         private static EmailMessageSummary ToSummary(GmailMessageSummary m)
             => new(m.Id, m.ThreadId, m.Subject, m.From, m.To, m.Date, m.Snippet);
     }

JobTrackerApi/Services/EmailProviders/IEmailProvider.cs

@@ -23,9 +23,21 @@ namespace JobTrackerApi.Services.EmailProviders
 
         /// <summary>Full message content (body + attachments metadata).</summary>
         Task<EmailMessageDetail> GetMessageAsync(string ownerUserId, string messageId, CancellationToken cancellationToken);
+
+        Task<EmailDeliveryResult> SendAsync(string ownerUserId, EmailDeliveryRequest request, CancellationToken cancellationToken);
     }
 
-    public sealed record EmailConnectionInfo(string ProviderKey, string Address);
+    public sealed record EmailConnectionInfo(string ProviderKey, string Address, bool CanSend = false);
+
+    public sealed record EmailDeliveryRequest(string To, string Subject, string BodyText, string? ThreadId = null);
+    public sealed record EmailDeliveryResult(string? ExternalMessageId, string? ExternalThreadId);
+
+    public sealed class EmailProviderDeliveryException(string category, bool uncertain, string message, Exception? innerException = null)
+        : Exception(message, innerException)
+    {
+        public string Category { get; } = category;
+        public bool Uncertain { get; } = uncertain;
+    }
 
     public sealed record EmailMessageSummary(string Id, string ThreadId, string Subject, string From, string To, DateTimeOffset? Date, string Snippet);
 

JobTrackerApi/Services/EmailProviders/ImapProvider.cs

@@ -57,6 +57,9 @@ namespace JobTrackerApi.Services.EmailProviders
                 attachments);
         }
 
+        public Task<EmailDeliveryResult> SendAsync(string ownerUserId, EmailDeliveryRequest request, CancellationToken cancellationToken) =>
+            throw new EmailProviderDeliveryException("unsupported_provider", false, "This IMAP connection does not include an outgoing-mail transport.");
+
         private static EmailMessageSummary ToSummary(ImapMessageSummary m)
             => new(m.Id, m.ThreadKey, m.Subject, m.From, m.To, m.Date, m.Snippet);
     }

JobTrackerApi/Services/EmailProviders/MicrosoftGraphProvider.cs

@@ -21,7 +21,7 @@ namespace JobTrackerApi.Services.EmailProviders
         public async Task<EmailConnectionInfo?> GetConnectionAsync(string ownerUserId, CancellationToken cancellationToken)
         {
             var connection = await _graph.GetConnectionAsync(ownerUserId, cancellationToken);
-            return connection is null ? null : new EmailConnectionInfo("microsoft", connection.MailAddress ?? "");
+            return connection is null ? null : new EmailConnectionInfo("microsoft", connection.MailAddress ?? "", MicrosoftGraphOAuthService.HasSendScope(connection.Scope));
         }
 
         public async Task<IReadOnlyList<EmailMessageSummary>> SearchAsync(string ownerUserId, string? query, int maxResults, CancellationToken cancellationToken)
@@ -57,6 +57,12 @@ namespace JobTrackerApi.Services.EmailProviders
                 attachments);
         }
 
+        public async Task<EmailDeliveryResult> SendAsync(string ownerUserId, EmailDeliveryRequest request, CancellationToken cancellationToken)
+        {
+            await _graph.SendAsync(ownerUserId, new MicrosoftGraphSendRequest(request.To, request.Subject, request.BodyText), cancellationToken);
+            return new EmailDeliveryResult(null, null);
+        }
+
         private static EmailMessageSummary ToSummary(MicrosoftGraphMessageSummary m)
             => new(m.Id, m.ConversationId, m.Subject, m.From, m.To, m.Date, m.Snippet);
     }