fix: daily report no longer flags a stack as silent when run mid-session

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01B3PXXn2tHBzdv6rYtGPz86

research/daily_report.py

@@ -193,7 +193,8 @@ def health_section(paper, live, today, alerts) -> list[str]:
                 alerts.append(f"The {name} stack was silent for {gap_min:.0f} min during market hours.")
             if n == 0:
                 alerts.append(f"The {name} stack wrote no heartbeats during market hours.")
-            elif last and last.strftime("%H:%M") < "15:45":
+            elif last and (datetime.now(ET).replace(tzinfo=None) - last).total_seconds() > 900 \
+                    and last.strftime("%H:%M") < "15:45":           # silent for 15+ min, before the close
                 alerts.append(f"The {name} stack went silent at {last:%H:%M} ET.")
         except Exception as e:  # noqa: BLE001
             lines.append(f"- {name}: ERROR {str(e)[:120]}")