Phase out Monk

[r03ert0]

Monk was abandoned in 2021, and it keeps BrainBox (and other of our apps) stuck with an old version of MongoDB.
We replace it from a more standard approach. Maybe the safest would be to have both Monk and the native mongodb driver coexisting for a period, and replace the uses of monk little by little. Like:

// Existing monk setup (unchanged)
const monk = require('monk');
const monkDb = monk(connectionString);

// New native driver setup
const { MongoClient } = require('mongodb');
const client = new MongoClient(connectionString);
await client.connect();
const nativeDb = client.db();  // database name comes from the URI