v1.5.2 - release-create upserts on every fire

create-release and upload-release-assets now PUT-or-POST so
every pipeline run converges the release record + asset links to
the current intent. Replaces v1.5.1's skip-if-exists behavior,
which left the release page stuck on the first pipeline's values
when a re-tag or rerun carried new content.

No other component changes.