SimulationSetup.cast() returns None for HFSSPI xlass

### 🔍 Before submitting the issue

- [x] I have searched among the existing issues
- [x] I am using a Python virtual environment

### 🐞 Description of the bug

Cell.simulation_setups internally calls
``.cast()`` on every object it returns. The ``cast()`` implementation
in the core library only handles a subset of solver types (HFSS,
SI_WAVE, SI_WAVE_DCIR, RAPTOR_X) and returns ``None`` for any type it
does not recognise — most notably ``HFSS_PI``. Those ``None`` values
are then silently discarded during the usual None-filtering step

### 📝 Steps to reproduce

NA

### 💻 Which operating system are you using?

Windows

### 📀 Which ANSYS version are you using?

_No response_

### 🐍 Which Python version are you using?

3.9

### 📦 Installed packages

```shell
NA
```

Start by tracing Cell.simulation_setups to the core library's cast() implementation and compare its handling of solver types with HFSS_PI. Confirm the None-filtering behavior, then verify that HFSS_PI setup objects are retained rather than discarded.

Written by the indexing model from the issue text.