b501ba9620
Every PostgreSQL test carries Category=RequiresDocker and the pipeline filters that category out, so the provider production runs on was never exercised and two upgrade-path bugs reached it in a row. Nothing covered the whole startup sequence either - code and schema migrations interleaved the way the migration service orders them. - run both database stages through JellyfinMigrationService against a seeded library and against a fresh install - take the server from JELLYFIN_TEST_POSTGRES when it is set, else start a container - add a pipeline step that runs the PostgreSQL tests on every push and pull request, with the server inside the step: the kubernetes backend has no docker daemon, and a service container deadlocks on the workspace volume