merge
Merge N Bedrock pack zips into one.
Return
the merged zip's File on success, null on failure
Parameters
inputZips
the per-backend Bedrock pack zips, ordered by priority (later entries win on plain-file collisions)
outputZip
where to write the merged zip
stableMergedPackUuid
the proxy-side stable UUID for the merged pack's header.uuid (so Bedrock clients cache it across re-merges). The module UUID is derived deterministically from this.