fix(cron): show schedule details and run state in _list_jobs() output

_list_jobs() only displayed job name, id, and schedule kind (e.g. "cron"),
omitting the actual timing and run state. The agent couldn't answer
"when does this run?" or "did it run?" even though CronSchedule and
CronJobState had all the data.

Now surfaces:
- Cron expression + timezone for cron jobs
- Human-readable interval for every jobs
- ISO timestamp for one-shot at jobs
- Enabled/disabled status
- Last run time + status (ok/error/skipped) + error message
- Next scheduled run time

Fixes #1496

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

nanobot/agent/tools/cron.py

@@ -147,7 +147,41 @@ class CronTool(Tool):
         jobs = self._cron.list_jobs()
         if not jobs:
             return "No scheduled jobs."
-        lines = [f"- {j.name} (id: {j.id}, {j.schedule.kind})" for j in jobs]
+        lines = []
+        for j in jobs:
+            s = j.schedule
+            if s.kind == "cron":
+                timing = f"cron: {s.expr}"
+                if s.tz:
+                    timing += f" ({s.tz})"
+            elif s.kind == "every" and s.every_ms:
+                secs = s.every_ms // 1000
+                if secs >= 3600:
+                    timing = f"every {secs // 3600}h"
+                elif secs >= 60:
+                    timing = f"every {secs // 60}m"
+                else:
+                    timing = f"every {secs}s"
+            elif s.kind == "at" and s.at_ms:
+                from datetime import datetime, timezone
+                dt = datetime.fromtimestamp(s.at_ms / 1000, tz=timezone.utc)
+                timing = f"at {dt.isoformat()}"
+            else:
+                timing = s.kind
+            status = "enabled" if j.enabled else "disabled"
+            parts = [f"- {j.name} (id: {j.id}, {timing}, {status})"]
+            if j.state.last_run_at_ms:
+                from datetime import datetime, timezone
+                last_dt = datetime.fromtimestamp(j.state.last_run_at_ms / 1000, tz=timezone.utc)
+                last_info = f"  Last run: {last_dt.isoformat()} — {j.state.last_status or 'unknown'}"
+                if j.state.last_error:
+                    last_info += f" ({j.state.last_error})"
+                parts.append(last_info)
+            if j.state.next_run_at_ms:
+                from datetime import datetime, timezone
+                next_dt = datetime.fromtimestamp(j.state.next_run_at_ms / 1000, tz=timezone.utc)
+                parts.append(f"  Next run: {next_dt.isoformat()}")
+            lines.append("\n".join(parts))
         return "Scheduled jobs:\n" + "\n".join(lines)
 
     def _remove_job(self, job_id: str | None) -> str: