**Patch Plan**
- **`store.py` → `get_user`**: Apply identical normalization to the lookup key.
  ```python
  def get_user(email):
      return USERS.get(email.strip().lower())
  ```

**Regression Test**
```python
def test_login_email_normalization():
    save_user(" Admin@Example.COM ", "hash_abc")
    assert login("admin@example.com", "hash_abc") is True
    assert login(" Admin@Example.COM ", "hash_abc") is True
```