Add a configurable bet slider with preset amounts

[Marvy247]

Replace the bet input with a slider showing pot-relative percentages (25%, 50%, 75%, 100%, all-in) with a manual override. Display the calculated amount next to the slider.

[NovaLabs4324]

@NovaLabs4324 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hello Maintainer,
I’m interested in being assigned this issue. I’ll handle the implementation carefully, test the changes, and submit a PR for review.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @NovaLabs4324 to this issue.

[Emoji-dot]

@Emoji-dot has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

I would like to work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Emoji-dot to this issue.