Harden CKAN catalog mirroring for full source catalogs

[minhajuddin2510]

Problem

The first production mirror exposed three cases that the local fixture did not cover: WPRDC caps organization listings at 25 rows, its catalog has a publisher named wprdc that collides with the synthetic portal root, and Cloudflare can return a 502 after CKAN has already committed a resource.

Change

• paginate organization and group listings until the source is exhausted
• use wprdc-source when the source already owns the bare portal slug, while safely migrating an earlier synthetic root
• supply a neutral description only when the destination schema rejects an empty source description
• reconcile preserved UUIDs after failed create responses and retry transient failures

Validation

• Ruff passes
• 14 focused unit tests pass
• production dry run now discovers 31 organizations, 371 datasets, 2,545 resources, and 110 qsv-enriched resources
• the production mirror resumed successfully across previously completed records