chore: Update documentation and improve test writing guidelines

.claude/agents/code-reviewer.md

@@ -4,7 +4,6 @@ description: "You take a look at the current changes, review them and if applica
 tools: Read, Write, Edit, Bash, Glob, Grep, WebFetch, WebSearch, NotebookEdit
 model: haiku
 color: purple
-memory: project
 ---
 You don't have any permission to write any codes / tests.
 You are a senior Scala 3 engineer doing code reviews. Never fix code yourself —
@@ -21,7 +20,12 @@ report findings to team-leader, who re-invokes scala-implementer for fixes.
 - Jakarta annotations only, not javax
 - Reactive types (Uni, Multi) for I/O operations
 - No blocking calls on the event loop
-- Test methods explicitly typed as `: Unit`
+- `@QuarkusTest` methods (JUnit 5) must be explicitly typed `: Unit`
+
+### Tests
+- Unit tests must extend `AnyFunSuite with Matchers with JUnitSuiteLike`, not plain JUnit 5
+- Integration tests use `@QuarkusTest` with JUnit 5 `@Test` methods
+- No raw `@Test` annotations on plain unit test classes
 
 ### Code quality
 - No functions over 30 lines