OBF multi-deployment guide uses the wrong host port variable and an unavailable Compose profile

[TaciteOFF]

The Open Beauty Facts example in docs/dev/how-to-develop-using-docker.md does not match the current Docker Compose configuration.

There seem to be two separate issues:

1. The guide changes PRODUCT_OPENER_PORT from 80 to 81, but
   docker/dev.yml also publishes PRODUCT_OPENER_HOST_PORT, which remains
   set to 80 in the copied .env file.

2. The guide sets COMPOSE_PROFILES=obf, but docker compose config --profiles
   currently only reports the off profile. postgres and redis-listener
   are assigned to that off profile.

3. The default Docker network name is hard-coded as product-opener in
   docker-compose.yml. As a result, the OFF and OBF Compose projects join
   the same internal network even though they have different
   COMPOSE_PROJECT_NAME values. Both projects then register identical
   network aliases such as backend, frontend, postgres and memcached,
   making service-name resolution ambiguous between the two deployments.

4. The Docker configuration still selects the off MongoDB database for an
   OBF flavor. Config2_docker.pm sets:

   $mongodb = $producers_platform ? "off-pro" : "off";

and Config_obf.pm reuses that value instead of selecting the obf
database. Therefore, an instance configured with
PRODUCT_OPENER_FLAVOR=openbeautyfacts and
PRODUCT_OPENER_FLAVOR_SHORT=obf still queries MongoDB database off.

The only available Compose profile is off.

postgres and redis-listener are not included with COMPOSE_PROFILES=obf.

The frontend configuration contains both:
published: "81"
published: "80"

Starting OBF alongside OFF therefore still attempts to bind host port 80.

Suggested changes :

1. Add PRODUCT_OPENER_HOST_PORT=81 to the documented OBF configuration.
2. Clarify whether OBF should keep COMPOSE_PROFILES=off, or add obf to the profiles of services required by every public flavor.
3. Consider updating env/env.obf so it also overrides the domain, host port and Minion queue required to run OBF alongside OFF.
4. Make the default Product Opener network name configurable or project-scoped, for example:

networks:
  default:
    name: ${PRODUCT_OPENER_NETWORK:-product-opener}

5. Select the MongoDB database from the configured flavor, or introduce an explicit environment variable such as MONGODB_DATABASE. For example, PRODUCT_OPENER_FLAVOR_SHORT=obf should result in mongodb=obf.

[pranavchoudhary-tech]

I'd like to take this up. I can fix the OBF documentation in how-to-develop-using-docker.md, update the Docker Compose network scoping to ${PRODUCT_OPENER_NETWORK:-product-opener}, and update MongoDB database selection for OBF in Config2_docker.pm.