chore: document application setup for Freiburg

[mirdono]

This PR extends the previously added partner documentation for the city of Freiburg. They are primarily interested in UC0.0, harvesting via OParl, and UC1 concerning Restricted Mobility Zones.

Proposed approach

This builds upon the documentation added in #101. Primarily it extends the overall README with (more) information on harvesting data via OParl and UC1. The partner-oriented README was extend with some Freiburg-specific information. Finally, a Freiburg-specific docker-compose override override was added. This configuration (partially) disables services that are not relevant for Freiburg and contains some template configuration for services that are relevant.

How to test

• Read all added documentation and assess whether it is factually correct and
  complete.
• Add the Bamberg-specific docker compose override to your .env and ensure the
  stack can be properly started. Note, it is expected that some services do not
  function correctly due to placeholder values in their configuration.

Notes

• The example configuration for AI service's API keys may be subject to change depending on the following PRs:
  • NER service
  • codelist-labelling service

Related tickets

• LBRON-1458

[mirdono]

As discussed on standup of 28 May 2026, merged without explicit review as we want to get it out to the partners.