feat: implement maximum participants limit

[dev-kraken]

Implement Maximum Participants Limit

This PR introduces a feature to limit the number of participants in a room.

Changes

• Added MAX_PARTICIPANTS environment variable in wrangler.toml for example MAX_PARTICIPANTS = 10
• Updated loader function to parse and validate MAX_PARTICIPANTS
• Modified Lobby component to use maxParticipants for determining room capacity
• Implemented UI changes to show when a room is full and prevent joining

How to test

1. Set different values for MAX_PARTICIPANTS in wrangler.toml
2. Run the application and try to join a room
3. Verify that the room becomes full when the number of participants reaches the set limit
4. Check that the UI updates correctly (button disabled, "Room Full" message shown)

Notes for reviewers

• Ensure that the error handling for invalid MAX_PARTICIPANTS values is sufficient
• Consider if we need additional logging or error reporting for when MAX_PARTICIPANTS is not set or invalid

close #140

[third774]

Hey @dev-kraken thanks for the PR. There are some changes I'm going to make before merging this — I think I'll likely keep your commit and create a new branch/PR from it.