Fix: store the grounds information on the ModerationCase

app/lib/admin/actions/moderation_case_resolve.dart

@@ -124,6 +124,7 @@ Closes the moderation case and updates the status based on the actions logged on
       }
 
       mc.status = status!;
+      mc.grounds = grounds;
       mc.violation = violation;
       mc.reason = reason;
       tx.insert(mc);

app/test/admin/moderation_case_resolve_test.dart

@@ -90,6 +90,8 @@ void main() {
       fn: () async {
         final mc = await _prepare(apply: null);
         expect(await _close(mc.caseId), 'no-action');
+        final closed = await adminBackend.lookupModerationCase(mc.caseId);
+        expect(closed!.grounds, ModerationGrounds.none);
       },
     );
 
@@ -119,6 +121,9 @@ void main() {
           await _close(mc.caseId, reason: 'The package violated our policy.'),
           'moderation-applied',
         );
+        final closed = await adminBackend.lookupModerationCase(mc.caseId);
+        expect(closed!.grounds, ModerationGrounds.policy);
+        expect(closed.violation, 'scope_of_platform_service');
 
         // cleanup does remove case after the threshold is reached
         await _verifyCaseExistence(mc.caseId, true);

app/test/admin/moderation_case_test.dart

@@ -187,7 +187,7 @@ void main() {
           'isSubjectOwner': false,
           'url': null,
           'status': 'no-action',
-          'grounds': null,
+          'grounds': 'none',
           'violation': 'none',
           'reason': null,
           'appealedCaseId': null,