[Phase 7] End-to-end test scenarios and bug fixes

[MohamedRamadanSaudi]

Task

Manually verify all flows end-to-end. Fix any issues found.

Checklist

• Create group → meeting auto-created → owner is admin member
• Non-member cannot access group detail (403)
• Send invite → email received → accept → user is member
• Email mismatch on accept → rejected
• Expired token → correct error message
• 2 group members join meeting → session auto-starts (bot joins)
• 1 leaves → session auto-stops
• Guest (non-member) in room → does not count toward threshold
• Group session visible to all members
• Chatbot answers questions about group sessions
• Chatbot rate limit at 20 req/min