fix(bandcamp_importer): namespace label cache key on discography pages

[chaban-mb]

Code and PR written by AI-tool

Problem

Fixes #795

On discography/band pages (e.g. https://hibernate.bandcamp.com), the script looks up both artist and label relations for the page URL. The label lookup was using the bare URL as its cache key — the same key used by the artist lookup. When a label was found, its MBID was cached under the bare URL.

On subsequent album page visits, resolveMBID(root_url) (line 631) would find that cached label MBID under the bare URL and incorrectly assign it to release.artist_credit[0].mbid, causing MusicBrainz to reject the import with:

Invalid artist_credit.names.0.mbid

Evidence from localStorage cache (before fix)

{
    "https://hibernate.bandcamp.com": {
        "urls": ["https://musicbrainz.org/label/ebd021f8-89b9-4363-8977-3751be350572"]
    }
}

A label MBID stored under the bare URL key — read by resolveMBID() as if it were an artist.

Fix

Add a label: prefix to the cache key on line 781, matching the pattern already used on album pages (line 610):

-mblinks.searchAndDisplayMbLink(cleanURL, 'label', insertLinkCb, undefined, onSearchComplete);
+mblinks.searchAndDisplayMbLink(cleanURL, 'label', insertLinkCb, `label:${cleanURL}`, onSearchComplete);

Cache after fix

{
    "https://hibernate.bandcamp.com": { "urls": [] },
    "label:https://hibernate.bandcamp.com": {
        "urls": ["https://musicbrainz.org/label/ebd021f8-89b9-4363-8977-3751be350572"]
    }
}

Label MBID is now namespaced. resolveMBID(root_url) correctly finds nothing (empty artist result), so no bogus MBID is seeded into the artist credit.

Testing

Tested on https://hibernate.bandcamp.com/album/the-state-of-shining (the example from #795). After clearing the localStorage cache and revisiting the page, the import button works correctly without the Invalid artist_credit error.

[arsinclair]

I suspect that it is the same problem that leads to #797. Could you verify that this fix also resolves that problem?
Example release: https://dronarivm.bandcamp.com/album/air-signs

Also, do you think it makes sense to prefix artist lookups as well, so there's never an ambiguity?

[chaban-mb]

Example release: https://dronarivm.bandcamp.com/album/air-signs

Inserts a label link for me there. But this won't fix existing cache. That would require waiting for it to expire, manually clearing or bumping cache key version.

Also when a Bandcamp page is linked to both an artist and a label it will only show one of them. (So far it's always the label)
E.g. https://altersynth.bandcamp.com/

Also, do you think it makes sense to prefix artist lookups as well, so there's never an ambiguity?

Can't hurt I guess.