fix: preserve debug info across snapshot re-fetch + widen refresh filter

- refreshDebug state lives in parent (InstrumentDashboard) so it survives
  fetchSnapshotSilent re-render (ExplanationScore no longer loses debugInfo
  when onRefreshDone triggers setLoading → unmount)
- fetchSnapshotSilent: re-fetches snapshot without setLoading(true) so
  ExplanationScore stays mounted with its state
- Refresh filter now catches rows where prediction_json is empty even if
  actual_json is populated, and handles '[]' / null variants

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/routers/causal_lab.py

@@ -1462,7 +1462,10 @@ def refresh_auto_analyses():
                 "pred_keys":    list(json.loads(pred).keys())   if pred   not in (None, "", "{}", "null") else [],
             })
 
-        rows = [r for r in all_rows if (r["actual_json"] or "") in (None, "", "{}", "null")]
+        _empty = (None, "", "{}", "null", "[]")
+        rows = [r for r in all_rows if
+                (r["actual_json"]     or "") in _empty or
+                (r["prediction_json"] or "") in _empty]
         print(f"[refresh] {len(rows)} analyses with empty actual_json out of {len(all_rows)} total", flush=True)
         conn.close()