Init: possible confusion if base+modified schemas already exist but local project dir doesn't

Seen the following case:

• configuration file "base" and "modified" schemas already exist in the database
• the project directory does not exist yet

In this scenario, db-sync will download the MM project at a particular version, but it does not check project ID first. This is a potential problem, because db-sync may try to download a project that is incompatible with the data already stored in the database - this can result in trying to fetch project at e.g. version 1234, but project may not even exist in such version, so the project download will fail.

The fix should be to check project ID before project's download, and fail with error if they do not match.

Inspecciona el flujo de inicialización en el que db-sync descarga el proyecto de Mergin Maps y sigue cómo se leen de la base de datos los esquemas base y modificados existentes. Comprueba el ID del proyecto antes de la descarga; la tarea estará terminada cuando un ID incompatible produzca un error en lugar de intentar la descarga.