refactor(run): Run.__init__ does not call super().__init__()

[MAfarrag]

Context

PR #149 added type annotations to `Run.init` which made an
existing inheritance defect more visible. `Run` inherits from
`Catchment` but its `init` only sets `self.Qsim` without
calling `super().init()`.

Problem / Current Behaviour

```python
class Run(Catchment):
def init(self, *args, **kwargs):
self.Qsim: np.ndarray | pd.DataFrame | None = None
```

Instantiating `Run()` directly creates an object missing all 45+
Catchment attributes. The class only works because callers construct
a `Catchment` first, populate its attributes via `read_*()` methods,
and then call `Run` methods on the same object.

Affected locations

File	Symbol	Notes
`src/Hapi/run.py:35-37`	`Run.init`	Missing `super().init()`

Proposed Solution

Either:

1. Add `super().init(*args, **kwargs)` to `Run.init`
2. Or document the intended usage pattern (construct Catchment, then
   call Run methods) and remove the misleading `init`

Effort Estimate

Size: `S`

Definition of Done

• `Run.init` either calls `super().init()` or is removed
• Direct `Run()` instantiation either works or raises a clear error
• Existing tests pass

[MAfarrag]

Closed: created in error. These are follow-up items from PR #152 review, not standalone issues.