Allow passing PCM data as slices instead of Vec

[revmischa]

ChatGPT recommended using slices because we can avoid extra allocations and ownership transfer when adding PCM data.

1. Parameter Type:
   • Changed the samples parameter from Vec to &[f32] in both the public and internal methods. This allows you to pass a slice directly without allocating a new Vec.
2. Ownership:
   • Since slices are borrowed references, there’s no ownership transfer, which is more efficient.
3. Usage of as_ptr():
   • Slices can still provide a raw pointer using .as_ptr(), so the FFI call remains unchanged.

Might be a breaking change though, if we care

[murl-digital]

It shouldn't be a breaking change, vecs are borrowed as slices automatically in most cases.