beta.19's on-disk discovery required site.json per locale, which
silently dropped locales that author only per-locale page overrides
(pages/{id}.json) and a shared.json — the common pattern for sites
where the brand name stays the same across languages. coastal hit
this after the beta.22 bump: locale dropdown disappeared, hreflang
collapsed.

Discovery now matches the pre-beta.19 glob behavior: any locale dir
with any of site.json / shared.json / pages/ counts as present.

Verified end-to-end on a coastal-pattern fixture.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>