fix: toLocalDateTime 변환 강화 — 타입 불일치 로깅 + toString 폴백

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

src/main/java/gc/mda/signal_batch/monitoring/controller/MonitoringController.java

@@ -228,14 +228,23 @@ public class MonitoringController {
         return quality;
     }
 
-    private static LocalDateTime toLocalDateTime(Object raw) {
+    private LocalDateTime toLocalDateTime(Object raw) {
-        if (raw instanceof java.sql.Timestamp ts) {
+        if (raw == null) return null;
-            return ts.toLocalDateTime();
+        if (raw instanceof LocalDateTime ldt) return ldt;
-        } else if (raw instanceof java.time.OffsetDateTime odt) {
+        if (raw instanceof java.sql.Timestamp ts) return ts.toLocalDateTime();
-            return odt.toLocalDateTime();
+        if (raw instanceof java.time.OffsetDateTime odt) return odt.toLocalDateTime();
-        } else if (raw instanceof LocalDateTime ldt) {
+        if (raw instanceof java.time.Instant inst) {
-            return ldt;
+            return inst.atZone(java.time.ZoneId.systemDefault()).toLocalDateTime();
+        }
+        log.warn("Unexpected temporal type: {} (class={})", raw, raw.getClass().getName());
+        try {
+            String s = raw.toString();
+            if (s.contains("+") || s.endsWith("Z")) {
+                return java.time.OffsetDateTime.parse(s).toLocalDateTime();
+            }
+            return LocalDateTime.parse(s.replace(" ", "T"));
+        } catch (Exception e) {
+            return null;
         }
-        return null;
     }
 }