rebrand educool rooms

I think the word rooms gives the user an impression that this a private video chatting app for dating or smthing, or like omegle random videos type shii,
rebranding educool rooms into classes or meetings or any other education-related word would be more suitable

Search the codebase for all occurrences of 'rooms' to understand its usage in UI labels, variable names, and API endpoints. The goal is to replace it with a more education-appropriate term like 'classes' or 'meetings' consistently. Check for any database schema references or configuration files that might also need updating. After making changes, run the existing tests to ensure functionality is preserved.

索引モデルが issue の本文から書いたものです。