Convert lists of values to np.array()

### 📝 Description of the feature

OptiSLang server sends:
- [ ] `vector`, `matrix` as data type `list` or `str`
- convert this to `np.array()` for user convenience
- [ ] xydata, signal as `dict` (e. g. {'channels': List[float] ..)
- create classes `XYdata` and `Signal` to store these

No files, tests, or entry points are named. Start by locating the code that parses OptiSLang server responses and the existing handling for vector, matrix, xydata, and signal values. Done means list or string vectors and matrices are exposed as NumPy arrays, with defined XYdata and Signal classes for the dictionary responses, plus coverage for these cases.

Written by the indexing model from the issue text.