fix: stop asking for dumps the collection can make

The Wanted page listed 79 dumps the collection already produces,
such as a Kickstart's byte-swapped words or the halves of a C128
character ROM. The pipeline now records which missing dumps can be
derived, in derivable.json, and the page moves them to a section of
their own that names the held file and the transform.

.github/workflows/deploy-site.yml

@@ -51,6 +51,7 @@ on:
       - "install.py"
       - "database.json"
       - "release.json"
+      - "derivable.json"
       - "mkdocs.yml"
       - ".github/workflows/deploy-site.yml"
   workflow_dispatch: