[DPC-4950] Add exception class to JSON log format (#2860)

## 🎫 Ticket

https://jira.cms.gov/browse/DPC-4950

## 🛠 Changes

Adds exception class to JSON log format.

## ℹ️ Context

Allows for faster log searches.

## 🧪 Validation

Test updated.

log example from smoke test:
```
{"timestamp":"2026-01-05T18:03:49.477+0000",
"level":"ERROR",
"thread":"RxComputationThreadPool-1",
"logger":"gov.cms.dpc.aggregation.engine.JobBatchProcessor",
"message":"Failed to retrieve Patient",
"exception":"ca.uhn.fhir.rest.server.exceptions.ResourceNotFoundException: No patient found with ID: \n\tat gov.cms.dpc.bluebutton.client.MockBlueButtonClient.formNoPatientException(MockBlueButtonClient.java:242)...",
"mdc":{"jobID":"e6fec28a-abe0-4906-88ad-2a738ce289b9","is_bulk":"true","organization_id":"0ab352f1-2bf1-44c4-aa7a-3004a1ffef12","aggregatorId":"fbc25203-a54e-4d88-83b5-d34134504962","batchID":"d7f12dae-db60-4d26-82ef-7f4575a14fe0","is_v2":"false"},
"environment":"local",
"application":"dpc-aggregation",
"version":"unknown_version",
"exceptionClass":"ResourceNotFoundException"}
```

Author: ashley-weaver

dpc-common/src/main/java/gov/cms/dpc/common/logging/DPCJsonLayout.java

@@ -2,6 +2,7 @@
 
 import ch.qos.logback.classic.pattern.ThrowableHandlingConverter;
 import ch.qos.logback.classic.spi.ILoggingEvent;
+import ch.qos.logback.classic.spi.IThrowableProxy;
 import com.google.re2j.Pattern;
 import io.dropwizard.logging.json.EventAttribute;
 import io.dropwizard.logging.json.layout.EventJsonLayout;
@@ -48,10 +49,16 @@ protected Map<String, Object> toJsonMap(ILoggingEvent event) {
         if(map.get(EXCEPTION) != null){
             String maskedExceptionDetails = maskPSQLData(map.get(EXCEPTION).toString());
             map.put(EXCEPTION, maskedExceptionDetails);
+            map.put("exceptionClass", getExceptionClass(event.getThrowableProxy()));
         }
         return map;
     }
 
+    private String getExceptionClass(IThrowableProxy e) {
+        String[] tokens = e.getClassName().split("\\.");
+        return tokens[tokens.length - 1];
+    }
+
     private void parseJsonMessageIfPossible(Map<String, Object> map,  String message) {
         try {
             Map<String, String> mappedMessage = splitToMap(message);

dpc-common/src/test/java/gov/cms/dpc/common/logging/DPCJsonLayoutUnitTest.java

@@ -9,15 +9,18 @@
 import io.dropwizard.logging.json.EventAttribute;
 import io.dropwizard.logging.json.layout.JsonFormatter;
 import io.dropwizard.logging.json.layout.TimestampFormatter;
+import org.hibernate.exception.ConstraintViolationException;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 import org.slf4j.LoggerFactory;
-import org.hibernate.exception.ConstraintViolationException;
-import java.sql.SQLException;
 
-import java.util.*;
+import java.sql.SQLException;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
@@ -185,6 +188,7 @@ public void testPostgresMaskingOnException() {
 
         Map<String, Object> map = dpcJsonLayout.toJsonMap(loggingEvent);
         assertEquals(expectedLogMessage, map.get("exception"));
+        assertEquals("ConstraintViolationException", map.get("exceptionClass"));
     }
 
     @Test