Application Template Lineage slug on Applications API

GET /api/v1/applications now accepts optional
application_template_lineage_slug and
application_template_lineage_slug_exclude query parameters. Pass one slug or a
comma-separated list to include only Applications on those template lineages, or
to exclude Applications on listed lineages. Both parameters can be used
together; for example,
?application_template_lineage_slug_exclude=utah-foster-care-volunteer returns
all Applications except those on the volunteer track. When both are set, exclude
is applied after include, so overlapping slugs are dropped; if every included
slug is also excluded, the result is empty.

Application responses (list and show) now include
application-template-lineage-slug alongside the existing template-slug
attribute. The lineage slug is stable across template versions; the template
slug identifies the specific template version in use.