fix(privacy): the instance's side of the reading of private studysets (ADR 0019)

An upload said to be encrypted must start as a sealed file does (HLKF,
version 1), so a readable file can't skip the PDF check by saying so. A
person's room counts the files a live asset row names and those claimed
within the week of grace, so a private studyset's rewrite near the limit
no longer fails for a week while pruning keeps the replaced files. Copy
reports are limited to 60 an hour per person. Tests: what goes with the
person, `counted` refused to anonymous people.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/learn/halkyon_learn_server/test/integration/explore/learner_count_test.dart

@@ -2,6 +2,7 @@ import 'dart:typed_data';
 
 import 'package:halkyon_base_server/base.dart';
 import 'package:halkyon_learn_server/src/explore/learner_count.dart';
+import 'package:halkyon_learn_server/src/explore/learning_count_endpoint.dart';
 import 'package:halkyon_learn_server/src/generated/protocol.dart';
 import 'package:serverpod/serverpod.dart';
 import 'package:serverpod_auth_idp_server/core.dart';
@@ -222,8 +223,51 @@ void main() {
 
         await learner();
         expect(await counted(), 1);
+        final gone = people.last;
         await deletePerson(session, people.removeLast());
         expect(await counted(), 0);
+        // Nothing of theirs stays behind, whatever the count says.
+        expect(
+          await CountedLearner.db.count(
+            session,
+            where: (t) => t.authUserId.equals(gone),
+          ),
+          0,
+        );
+        expect(
+          await LearningCopy.db.count(
+            session,
+            where: (t) => t.authUserId.equals(gone),
+          ),
+          0,
+        );
+      });
+
+      test('a person reports at most an hour\'s worth of times', () async {
+        final copy = await learner();
+        final person = people.last;
+        final report = [
+          CopyReport(
+            publicationId: japanese.publicId.uuid,
+            studysetIds: [copy],
+          ),
+        ];
+        // The learner reported once already.
+        for (var i = 1; i < copyReportsPerHour; i++) {
+          expect(
+            await endpoints.learningCount.reportCopies(
+              signedIn(person),
+              report,
+            ),
+            isTrue,
+          );
+        }
+
+        expect(
+          await endpoints.learningCount.reportCopies(signedIn(person), []),
+          isFalse,
+        );
+        expect(await counted(), 1);
       });
 
       test('reports are kept only while the person chose to be counted, '
@@ -274,6 +318,10 @@ void main() {
           ),
           throwsA(isA<ServerpodInsufficientAccessException>()),
         );
+        await expectLater(
+          endpoints.learningCount.counted(signedIn(person, anonymous: true)),
+          throwsA(isA<ServerpodInsufficientAccessException>()),
+        );
         expect(await CountedLearner.db.count(session), 0);
       });
     },