useShadowStyles keys its <style> by the label and overwrites an existing
tag with the same key, so two components sharing a label keep only the
last one's CSS in a shared shadow root. The regions list lost its sheet
this way to the region card, which had kept the list's label when it was
extracted.
check:shadow-style-labels-unique (gates:pre) fails any label two calls
share, globally rather than per shadow root, so a copied or forked
component is caught when it is copied. It reads the real parsers,
classifies every reference to the function (a rebinding, .call, a
re-export or a namespace import fails instead of hiding a call),
cross-checks the AST against the token stream, and covers the other
ways two calls share a key: unlabelled calls under the dev server's
per-component key, and a fixed label over CSS that varies per caller.
countries-map.vue, a fork of research-map.vue, carried the same label;
it is now 'countries-map', with the country-posters bundle rebuilt and
the tree regenerated. The composable's JSDoc called the label a
debugging name; it now says it is the key.
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