feat(messaging): sync draft emails and edit them in the thread composer (#22178)

Stop excluding drafts from sync across all three providers (Gmail DRAFT
label, Microsoft/IMAP Drafts folder) and add an isDraft boolean field on
Message so drafts are queryable by the API and AI agents.

Drafts render in the thread with a Draft tag; clicking one opens the
existing reply composer pre-filled with the draft's recipients, subject
and body, and Send reuses the existing send-email flow.

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Co-authored-by: Félix Malfait <felix.malfait@gmail.com>

packages/twenty-server/src/engine/core-modules/messaging/dtos/timeline-thread.dto.ts

@@ -35,4 +35,7 @@ export class TimelineThreadDTO {
 
   @Field()
   participantCount: number;
+
+  @Field()
+  lastMessageIsDraft: boolean;
 }

packages/twenty-server/src/engine/core-modules/messaging/services/timeline-messaging.service.ts

@@ -106,6 +106,7 @@ export class TimelineMessagingService {
               lastMessageBody: lastMessage.text ?? '',
               lastMessageReceivedAt: lastMessage.receivedAt ?? new Date(),
               numberOfMessagesInThread: messageThread.messages.length,
+              lastMessageIsDraft: lastMessage.isDraft ?? false,
             };
           }),
           totalNumberOfThreads,