fix: Game Mode dropdown has duplicate options & no selected-state for difficulty/animation toggles

[Mkalbani]

File: src/components/AccountSettings.tsx

Problem
In the "Game setting" tab, the Game Mode <select> has:
Classic Mode
Mode
Mode
The two Mode entries are a copy/paste leftover. Also the Difficulty (Easy/Medium/Hard) and Animation Speed (Slow/Normal/Fast) button groups have no selected state — no useState, no styling on the active button.

Expected

• Replace the duplicate placeholders with real game modes sourced from src/data/gameModes.ts.
• Track difficulty and animationSpeed in component state, render them through the same pattern as the Theme toggle.
• Persist selections into localStorage next to the existing settings key.

Acceptance

• Only valid modes appear in the dropdown.
• Clicking a difficulty / animation speed visibly highlights it and persists on reload.

[webdevayo]

Hello Maintainer, would like to work on this project. Please assign to me ...

[jesutobaadedejidev]

I would like to work on this. Do assign it to me.

[spiffamani]

I'm a full-stack Software Engineer
I'd love to take this on — thanks for considering me

[gloskull]

Can i work on this?