Demo: Billing & Team Management Polish

This demo changelog focuses on operational improvements that make billing, team management, and settings easier to trust.

Billing status summary - Current plan, renewal state, and usage limits are easier to compare.
Invite flow polish - Member invitations now give clearer feedback after each action.
Organization settings cleanup - Details, members, billing, and danger-zone actions are easier to scan.

More consistent form feedback - Save states, validation messages, and disabled states now follow the same pattern.
Sharper navigation labels - Settings pages use shorter labels that match the sidebar structure.