feat(sync): export guild sync diagnostics via IPC

Handle export-guild-sync-diagnostics and return JSON for clipboard copy in UI.

Co-authored-by: Cursor <[email protected]>

index.js

@@ -140,6 +140,15 @@ async function dispatchUiMessage (platform, msg, hooks = {}) {
     pushState()
     return true
   }
+  if (t === 'export-guild-sync-diagnostics') {
+    const data = platform.exportGuildSyncDiagnostics(msg.guildId)
+    send({
+      type: 'guild-sync-diagnostics-exported',
+      json: JSON.stringify(data, null, 2)
+    })
+    pushState()
+    return true
+  }
   if (t === 'mark-onboarding-explore-shown') {
     await platform.markOnboardingExploreShown()
     pushState()