fix: force apps to wait for mysql to actually become healthy

[pwnage101]

Note in the following recording:

1. While mysql80 is in "Waiting", some of the services are stuck in "Created".
2. Only AFTER mysql80 progresses to "Healthy", the rest of the apps begin starting.
3. The payoff: enterprise-access is immediately running after dev.up.
   • This is a massive UX improvement over the old experience where NONE of the apps actually started (they were always stuck on an error connecting to MySQL). ALL apps needed to be manually restarted which is extremely annoying.

Screen.Recording.2026-06-10.at.15.53.23.mov

[Copilot]

Pull request overview

This PR improves devstack startup behavior by adding an explicit MySQL healthcheck and updating service dependencies so application containers wait for MySQL to become healthy (not merely started), preventing “created/stuck” states and reducing the need for manual restarts.

Changes:

• Added a healthcheck to the mysql80 service that pings MySQL over TCP to avoid false-positives during first-time initialization.
• Updated multiple services’ depends_on to use condition: service_healthy for mysql80 (and service_started for other dependencies) so apps start only after MySQL is actually ready.

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[kiram15]

Very helpful, thank you for this change!