feat(cron): add one-time 'at' schedule to skill docs and show timezone in system prompt

nanobot/agent/context.py

@@ -73,7 +73,9 @@ Skills with available="false" need dependencies installed first - you can try in
     def _get_identity(self) -> str:
         """Get the core identity section."""
         from datetime import datetime
+        import time as _time
         now = datetime.now().strftime("%Y-%m-%d %H:%M (%A)")
+        tz = _time.strftime("%Z") or "UTC"
         workspace_path = str(self.workspace.expanduser().resolve())
         system = platform.system()
         runtime = f"{'macOS' if system == 'Darwin' else system} {platform.machine()}, Python {platform.python_version()}"
@@ -88,7 +90,7 @@ You are nanobot, a helpful AI assistant. You have access to tools that allow you
 - Spawn subagents for complex background tasks
 
 ## Current Time
-{now}
+{now} ({tz})
 
 ## Runtime
 {runtime}