Initial certificate system

backend/tests/test_captcha.py

@@ -0,0 +1,9 @@
+from app.services.captcha import make_captcha, verify_captcha
+
+
+def test_captcha_can_only_be_used_once():
+    captcha = make_captcha()
+    captcha_id = captcha["captcha_id"]
+    # The real code is intentionally not exposed. This test locks in one-time consumption behavior.
+    assert not verify_captcha(captcha_id, "bad")
+    assert not verify_captcha(captcha_id, "bad")