chore: scheduler runtime state + spike findings

- cron/jobs.json: heartbeat last_run / next_run actualizat de scheduler-ul live
- tasks/spike-planning-findings.md: validare empirică Spike Step 0 pentru
  planning agent subprocess (claude -p + skills gstack + --resume round-trip)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cron/jobs.json

@@ -269,9 +269,9 @@
     "prompt": "Heartbeat check. Rulează src/heartbeat.py printr-un scurt raport de status.\nDacă nu e nimic de raportat (email=0, calendar nu are evenimente <2h, kb ok), răspunde doar cu HEARTBEAT_OK și oprește-te — nu trimite mesaj.\nDacă e ceva: raport scurt pe Discord #echo-work.",
     "allowed_tools": [],
     "enabled": true,
-    "last_run": "2026-04-26T16:00:00.003767+00:00",
+    "last_run": "2026-04-26T18:00:00.003601+00:00",
     "last_status": "ok",
-    "next_run": "2026-04-26T18:00:00+00:00"
+    "next_run": "2026-04-27T06:00:00+00:00"
   },
   {
     "name": "night-execute",
@@ -289,4 +289,4 @@
     "last_status": null,
     "next_run": null
   }
-]
+]