PIN a 4 cifre: migrazione 017, login-pin, pin-users, PUT pin, capoturno via PIN (#59)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/backend/tests/test_migrations.py

@@ -149,3 +149,22 @@ class TestVisionRecipeDirMigration:
         assert "vision_recipe_dir" not in cols()
         command.upgrade(cfg, "head")  # e di nuovo su
         assert "vision_recipe_dir" in cols()
+
+
+class TestUserPinMigration:
+    """017_user_pin: users.pin_hash / pin_failed_count / pin_locked_until, su e giu (#59)."""
+
+    def test_017_upgrade_and_downgrade(self, sqlite_database_url):
+        db_path, _ = sqlite_database_url
+        cfg = _alembic_config()
+        new = {"pin_hash", "pin_failed_count", "pin_locked_until"}
+
+        def cols():
+            return {c["name"] for c in _inspect(db_path).get_columns("users")}
+
+        command.upgrade(cfg, "head")
+        assert new <= cols()
+        command.downgrade(cfg, "016_vision_recipe_dir")
+        assert not (new & cols())
+        command.upgrade(cfg, "head")  # e di nuovo su
+        assert new <= cols()