feat: add postgres section for retire-dataset dag

[tombrooks248]

What type of PR is this? (check all applicable)

• Refactor
• Feature
• Bug Fix
• Optimization
• Documentation Update

Description

Adds a postgres task to the retire-dataset DAG. It runs after discover, alongside files, and runs the Postgres loader image with the command ./retire.sh (digital-land/digital-land-postgres#31), passing DATASET_NAME and the same DRY_RUN value as files. The loader removes the dataset's rows from entity, old_entity and entity_subdivided, or only counts them on a dry run. The DAG docs now describe the task and how removed rows can be loaded again.

Why

Part 2 of digital-land/digital-land-builder#64. Removing a dataset's files leaves its entities in Postgres, so its entity pages and API results stay live. This is what takes a retired dataset off the site.

Related Tickets & Documents

• Ticket Link
• Related Issue #
• Closes #

QA Instructions, Screenshots, Recordings

• Deployed this branch to development and ran retire-dataset with retire-dataset-test (not in the specification) as a dry run (run manual__2026-10-07T13:43:58):
  • guard passed and discover logged no user-facing files found for retire-dataset-test in development-collection-data.
  • postgres started development-sqlite-ingestion-task with command: ['./retire.sh'], DATASET_NAME: 'retire-dataset-test' and DRY_RUN: 'true', all rendered as plain strings.
  • The container logged Retiring retire-dataset-test rows from postgres (DRY_RUN=true) and then would remove 0 retire-dataset-test rows from each of entity, old_entity and entity_subdivided. It exited 0, which shows the task reaches the database with the task definition's credentials and removes nothing on a dry run.
• The loader's retire mode (feat: enable retire dataset function digital-land-postgres#31) was tested separately against a local PostGIS database. A dry run changed nothing, and DRY_RUN=false removed only the given dataset's rows. It is deployed to every environment, including production.

Added/updated tests?

We encourage you to keep the code coverage percentage at 80% and above. Please refer to the Digital Land Testing Guidance for more information.

• Yes
• No, and this is why: please replace this line with details on why tests
  have not been included
• I need help with writing tests

[optional] Are there any post deployment tasks we need to perform?

[optional] Are there any dependencies on other PRs or Work?