Simplify: use Zeabur MySQL directly via SQL_DSN secret

Fix: stderr redirect, add connectivity test, better logging

Foreground import after new-api starts, with visible logs

Fix: keep shell alive so background import process survives

Background import: start new-api immediately, import data async

Robust init: check db existence, handle root auth states

Use remote mysqldump for data import instead of base64 secret

Fix: use marker file for init, handle pre-initialized datadir

Fix: allow root TCP connection for new-api

Use mysql:8.0 image as base

Fix: use debian base with MySQL 8 APT repo

MySQL 8 + new-api, all secrets from env vars