Update Notes

This update focuses on database stability, MySQL/MariaDB compatibility, and safer Velocity backend routing checks.

- Fixed MySQL 8 schema migrations by removing unsupported ADD COLUMN IF NOT EXISTS usage.
- Improved migration safety with metadata-based checks before adding columns or indexes.
- Added detailed schema migration logs for migration start, existing/created columns, existing/created indexes, failures, and completion timing.
- Improved backend readiness checks on Velocity.
- When both auth-entry and post-auth servers are enabled and defined, ProudAuth now verifies both before allowing the player through.
- Prevents cases where the auth server is available but the post-auth target is offline or not responding.
- Regenerated the universal jar with the latest fixes.

Important: This update is recommended for all networks using MySQL 8 or the auth-entry/post-auth routing flow.