[Feature Request] Improve button alignment for Theater Mode and add separate positioning for Fullscreen

[llc0930]

Is your feature request related to a problem? Please describe.
Yes, there are alignment and accessibility issues when buttons are placed below the player. Currently, the centering logic is statically fixed to the "Original size" player dimensions. Even when the "Automatic theater mode" option is enabled in the settings, the buttons remain aligned to the smaller player size rather than the wider theater layout.

Additionally, the lack of independent configurations for Fullscreen mode makes these buttons inaccessible unless the user scrolls down, which is counterintuitive during fullscreen playback.

Describe the solution you'd like
I would like to see two main improvements:

1. Dynamic Centering: Buttons placed below the player should dynamically detect the active player width (Normal vs. Theater Mode) and center themselves accordingly.
2. Separate Fullscreen Positioning: Introduce a dedicated position setting for Fullscreen mode. This would allow users to keep buttons below the player in windowed mode while choosing a different, more accessible placement for Fullscreen.

Describe alternatives you've considered
To be honest, because the current "below player" setting works poorly in Theater and Fullscreen modes, I’ve had to manually switch the buttons back to other positions to keep them functional, even though I'd prefer them below the player.

[VampireChicken12]

Thank you, the dynamic centering I can accomplish very easily but the full screen placement options will take a bit of planning