Enable Enter key to join room from code input

[Naitik868]

Changes

• Added Enter key support for submitting a valid 6-character room code.
• Added Show/Hide Code toggle for the room-code input.
• Added helper guidance explaining the 6-character room code format.
• Updated README.md to document the improved Join Room experience.

Issue

Closes #118

Testing

• Verified room-code validation remains unchanged.
• Verified Join Room remains disabled until 6 characters are entered.
• Verified Enter submits when the room code is valid.
• Verified Show/Hide Code toggles the input visibility.

[karan033-cybertech]

Bro, this is just a minor feature—try implementing something more major.

[Naitik868]

Bro, this is just a minor feature—try implementing something more major.

Thanks for the feedback. I have now added an additional feature: a Show/Hide Room Code toggle on the Join Room page, along with the Enter-key support. The PR has been updated with the new changes.

[Naitik868]

Thanks for the feedback. I have created a follow-up issue for a larger usability enhancement:

🔗 #118 — Add show/hide room code toggle on Join Room page

I am extending the Join Room experience beyond the initial Enter-key support and will update this PR with the additional usability improvement.