[Feature request] Allow micro-adjustments / fine-grained control for playback speed

### Describe your suggested feature In older versions of LibreTube, it was possible to make very small, precise adjustments to playback speed. Right now, the playback speed slider locks into fixed 0.25x step increments. While the new UI looks great, 0.25x steps are a bit too large when trying to find the perfect speed for fast-talking podcasts or lectures where something like 1.10x or 1.15x would be ideal. It would be amazing to get an option to change the step size (like 1% or 0.05x increments) or a toggle to switch the slider back to a continuous/granular adjustment mode for users who need fine-grained control. ### Other details I am attaching two images to show the difference. In the LibreTube screenshot, you can see the current setup which is locked into the specific dot intervals. In the NewPipe screenshot, they use a "Step" modifier system (1%, 5%, etc.) to allow micro-adjustments. I'm definitely not asking to copy their layout or UI style, but having that level of audio fine-tuning capability inside LibreTube's interface would be incredibly helpful. <img width="954" height="863" alt="Image" src="https://github.com/user-attachments/assets/f3d5f742-9033-4c11-a4d2-777ed2a40ea4" /> <img width="1807" height="1012" alt="Image" src="https://github.com/user-attachments/assets/02d661c3-865c-44fd-8b8b-6747e0d7df5b" /> ### Acknowledgements - [x] I have searched the existing issues and this is a new ticket, **NOT** a duplicate or related to another open issue. - [x] I have written a short but informative title. - [x] I will fill out all of the requested information in this form.