fix: implement robust multi-timestamp synchronization logic to prevent data regression

frontend/electron/services/backend.ts

@@ -62,18 +62,22 @@ export class BackendService {
         loginName: account.loginName,
         steamLoginSecure: account.steamLoginSecure,
         loginConfig: account.loginConfig,
-        sessionUpdatedAt: account.sessionUpdatedAt
+        sessionUpdatedAt: account.sessionUpdatedAt,
+        lastMetadataCheck: account.lastBanCheck,
+        lastScrapeTime: account.lastScrapeTime,
+        cooldownExpiresAt: account.cooldownExpiresAt
       }, { headers: this.headers });
     } catch (e) {
       console.error('[Backend] Failed to share account');
     }
   }
 
-  public async pushCooldown(steamId: string, cooldownExpiresAt?: string) {
+  public async pushCooldown(steamId: string, cooldownExpiresAt?: string, lastScrapeTime?: string) {
     if (!this.token) return;
     try {
       await axios.patch(`${this.url}/api/sync/${steamId}/cooldown`, {
-        cooldownExpiresAt
+        cooldownExpiresAt,
+        lastScrapeTime
       }, { headers: this.headers });
     } catch (e) {
       console.error(`[Backend] Failed to push cooldown for ${steamId}`);