uv identifies a workspace member by its declared project name, so the
same plugin enabled in two profiles declares one name twice and the
dependency sync fails with 'Two workspace members are both named ...'.
Metadata-only members (no build backend) now carry the unique member
key in their name, exactly like manifest-only members already do. A
buildable member keeps the name it declares, since uv verifies it
against the package metadata its backend produces.
0fc90369a5