Fix error display for previously failed but now successful posts

Update schedulerService.publishPost to clear the error field when a post is successfully republished.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: ae4037a0-2a6f-4530-9bac-79b543286bda
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/397bca8c-984f-43ff-841a-10897aeb8140/ae4037a0-2a6f-4530-9bac-79b543286bda/VDgoPyA

server/services/scheduler.ts

@@ -112,10 +112,11 @@ export class SchedulerService {
       throw new Error(`Unsupported platform: ${page.platform}`);
     }
 
-    // Update the scheduled post as published
+    // Update the scheduled post as published (clear any previous error)
     await storage.updateScheduledPost(scheduledPost.id, {
       publishedAt: new Date(),
       externalPostId,
+      error: null,
     });
 
     // Update post status