🪲 Initialize DB tables on app inizialitation

[jpelay]

Describe the bug
On #4862 I did a little hack by setting the DEBUG_MODE variable before main is executed. This is not ideal and @rix0rrr suggested a better alternative:

I think the better solution is probably to control the initialization order of all these things better, by making the tables class members of Database and initializing it when the app is created