Harden migrations, secret handling, database CI, and releases - #15

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5, rustsec/audit-check@69366f33c96575abad1ee0dba8212993eecbe998. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/