diag: error_log sync-event POSTs to trace missing toasts

Temporary diagnostic scaffolding — B-side logs every POST to the relay
(status + body snippet), A-side already console.debugs the GET result
via sync_debug. Lets us narrow down where the sender-side toast gets
lost.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

electron/package.json

@@ -1,6 +1,6 @@
 {
   "name": "hyprcrd",
-  "version": "1.8.1",
+  "version": "1.8.2",
   "description": "hyprcrd — self-hosted card manager",
   "main": "main.js",
   "scripts": {