[codex] Harden production database configuration

[jjoonleo]

Summary

• Add explicit local and test Spring profiles while hardening the production profile to require environment-provided database credentials.
• Pin production Hibernate DDL mode to validate, disable SQL logging, and disable Flyway baseline-on-migrate.
• Harden the deploy workflow so unsafe production database settings fail before restart.
• Replace CI's generated ignored application.properties with SPRING_PROFILES_ACTIVE=test and add static policy tests.
• Document the current production database configuration.

Validation

• ./gradlew test --tests devkor.ontime_back.security.DatabaseConfigurationPolicyTest --rerun-tasks

Note

• Full ./gradlew test still requires a MySQL 8 service on localhost:3306; the local Docker daemon was unavailable during implementation.