Adapt admin api to use new key format

Filter out deleted an previous version in count

Remove todo comment

Allow explicit ID specification

Update tests

tests/packages/backend/test_backend.py

@@ -119,6 +119,9 @@ def test_delete_client(test_client: TestClient) -> None:
     resp = test_client.get("/api/v1/clients/test")
     assert resp.status_code == 404
 
+    resp = test_client.get("/api/v1/clients/")
+    assert resp.status_code == 200
+
 
 def test_add_secret(test_client: TestClient) -> None:
     """Test adding a secret to a client."""