test(archunit): add Rule 2 coverage for importing and audit domains

MassImportService delegates to other domain services (no direct repo
access), and AuditService only touches its own AuditLogRepository —
both pass the boundary rule cleanly. Closes the known hole flagged
by Sara and Markus in PR #428.

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

backend/src/test/java/org/raddatz/familienarchiv/shared/ArchitectureTest.java

@@ -86,6 +86,20 @@ class ArchitectureTest {
             .and().resideInAPackage("..ocr..")
             .should().dependOnClassesThat(foreignJpaRepositoryFor("ocr"));
 
+    @ArchTest
+    static final ArchRule services_only_access_own_domain_repositories_importing =
+        noClasses()
+            .that().areAnnotatedWith(Service.class)
+            .and().resideInAPackage("..importing..")
+            .should().dependOnClassesThat(foreignJpaRepositoryFor("importing"));
+
+    @ArchTest
+    static final ArchRule services_only_access_own_domain_repositories_audit =
+        noClasses()
+            .that().areAnnotatedWith(Service.class)
+            .and().resideInAPackage("..audit..")
+            .should().dependOnClassesThat(foreignJpaRepositoryFor("audit"));
+
     // Rule 3: Infrastructure @Configuration classes must not end up scattered in domain packages.
     // Keeps cross-cutting setup (security, async, DB, storage) in dedicated packages
     // where it can be audited and reasoned about independently.