[Bug][UI/UX] Restore V button in battle

[Wlowscha]

Why am I making these changes?

Requested by @Xavion3 here to fix the bug reported on discord here and here.

What are the changes from a developer perspective?

Use the correct key name.

Screenshots/Videos

Before:

Pokerogue.Mozilla.Firefox.2025-03-01.20-58-58.mp4

After:

Pokerogue.Mozilla.Firefox.2025-03-01.21-00-42.mp4

How to test the changes?

Turn on the phone emulator in your browser and mash that V button.

Checklist

• I'm using beta as my base branch
• There is no overlap with another PR?
• The PR is self-contained and cannot be split into smaller PRs?
• Have I provided a clear explanation of the changes?
• Have I tested the changes manually?
• Are all unit tests still passing? (npm run test)
  • Have I created new automated tests (npm run create-test) or updated existing tests related to the PR's changes?
• Have I provided screenshots/videos of the changes (if applicable)?
  • Have I made sure that any UI change works for both UI themes (default and legacy)?