### Patch Plan
**File:** `store.py`  
**Function:** `get_user`  
**Edit:** Normalize the input email before lookup to match `save_user`'s normalization.

```python
def get_user(email):
    return USERS.get(email.strip().lower())
```

### Regression Test
```python
def test_login_email_normalization():
    save_user("  Admin@Lab.COM  ", "hash123")
    assert login("admin@lab.com", "hash123") == True
    assert login("ADMIN@LAB.COM", "hash123") == True
    assert login("  Admin@Lab.COM  ", "hash123") == True
```