remove contract test

ai/backend-context.md

@@ -20,6 +20,9 @@ intentionally omitted here - update this section as entities land.
   - Do not write unit tests for concrete repository implementations
     (e.g. `Postgres*Repository`). They are exercised by e2e tests.
     Use cases are tested with fake repositories.
+  - Do not write reflection-only contract tests for repository interface
+    method names, parameter counts, parameter names, or type hints. PHP
+    interfaces already enforce those signatures; test behavior instead.
   - Repository methods that find records by a foreign key should accept
     the related entity, not a raw id (e.g. `findBySet(Set $set)`, not
     `findBySetId(int $setId)`).