Fix: hide the spam action in Sent, Drafts and Scheduled

Marking your own outgoing mail as spam makes no sense, but the action
was offered in every non-junk folder: context menu, hover quick-actions,
viewer toolbar and its overflow menu, plus the "!" shortcut.

All surfaces now skip the action when the folder role is sent, drafts or
scheduled, and the shortcut is a no-op there. Scheduled messages were
already covered per-email via isScheduled; the role check additionally
covers the server-side Scheduled folder before that annotation loads.

The hover quick-actions bar gets a spamApplicable prop for this, since
it renders its buttons without knowing the folder.

components/email/thread-list-item.tsx

@@ -405,6 +405,7 @@ const SingleEmailItem = React.forwardRef<HTMLDivElement, SingleEmailItemProps>(
             onMarkAsSpam={onMarkAsSpam}
             onUndoSpam={onUndoSpam}
             isInJunk={currentMailboxRole === 'junk'}
+            spamApplicable={!['sent', 'drafts', 'scheduled'].includes(currentMailboxRole || '')}
           />
         )}
       </div>
@@ -875,6 +876,7 @@ export const ThreadListItem = React.forwardRef<HTMLDivElement, ThreadListItemPro
               onMarkAsSpam={onMarkAsSpam ? () => onMarkAsSpam(latestEmail) : undefined}
               onUndoSpam={onUndoSpam ? () => onUndoSpam(latestEmail) : undefined}
               isInJunk={currentMailboxRole === 'junk'}
+              spamApplicable={!['sent', 'drafts', 'scheduled'].includes(currentMailboxRole || '')}
             />
           )}
         </div>