feat(emails): add re-send for all emails, failed tab, and resend indicators

- Add resend_attempts and last_resent_at to email_logs schema and migrations
- Add POST /api/emails/logs/:id/resend and emailService.resendFromLog
- Add resendLog API and EmailLog.resendAttempts/lastResentAt
- Add All/Failed sub-tabs, resend button for all emails, re-sent indicator in logs and detail modal

Made-with: Cursor

frontend/src/lib/api.ts

@@ -492,7 +492,12 @@ export const emailsApi = {
   },
   
   getLog: (id: string) => fetchApi<{ log: EmailLog }>(`/api/emails/logs/${id}`),
-  
+
+  resendLog: (id: string) =>
+    fetchApi<{ success: boolean; error?: string }>(`/api/emails/logs/${id}/resend`, {
+      method: 'POST',
+    }),
+
   getStats: (eventId?: string) => {
     const query = eventId ? `?eventId=${eventId}` : '';
     return fetchApi<{ stats: EmailStats }>(`/api/emails/stats${query}`);
@@ -792,6 +797,8 @@ export interface EmailLog {
   sentAt?: string;
   sentBy?: string;
   createdAt: string;
+  resendAttempts?: number;
+  lastResentAt?: string;
 }
 
 export interface EmailStats {