feat(send): 'Send now' on the send-delay toast

The post-send undo toast ('scheduled to send' + Cancel send) now also offers a
'Send now' action that reschedules the delayed submission for immediate release,
so you can skip the undo window without waiting it out. Adds an optional
secondaryAction to the toast component and carries identityId on the pending
undo-send state so the reschedule can target the right identity.

app/(main)/[locale]/page.tsx

@@ -1428,6 +1428,27 @@ export default function Home() {
 
     toast.success(t('email_viewer.scheduled_send_created'), {
       duration: undoDurationMs,
+      secondaryAction: (pending.emailId && pending.identityId)
+        ? {
+            label: t('email_viewer.send_now'),
+            onClick: () => {
+              void (async () => {
+                try {
+                  await client.rescheduleEmailSubmission(
+                    pending.submissionId,
+                    pending.emailId!,
+                    pending.identityId!,
+                    new Date(Date.now() + 1000).toISOString(),
+                  );
+                  clearPendingUndoSend();
+                  if (isScheduledView) await fetchScheduledEmails(client);
+                } catch (error) {
+                  console.error('Failed to send now:', error);
+                }
+              })();
+            },
+          }
+        : undefined,
       action: {
         label: t('email_viewer.undo_send'),
         onClick: () => {