chore: redesign article localization before implementation

docs/design/screens/localization-metadata-api.md

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+# Localization: metadata and public API
+Board: RenewCMS Screens Localization. Frame: LocaleFrame. Data: locale-fixtures.js (single fixture source), tables in locale-spec.js. UI copy says "article", never "story". No revision numbers, IDs or HTTP status names in user-facing text.
+
+## L10 Metadata and public API
+Route: Search and sharing panel · /integration
+API: existing slug, SEO fields; proposed alternates[], lang; exact lookup by site + lang + slug; resolution by story_id
+
+Slug is unique per (site, lang). Exact lookup is by site + language + slug and never falls back. Language resolution and fallback use the stable story_id. Website URLs come from the site's Public URL pattern; without it the panel says "Public URL not configured" and links to the setting. Canonical is the localized page itself unless an override is set. SEO labels: "Fallback: French title", "No fallback", "Empty. English site default not used."
+
+| ID | State | Trigger | Selector | Sizes | Fixture |
+|---|---|---|---|---|---|
+| loc.seo.noFallback | Search and sharing: French | Localized slug, canonical, alternates, fallback labels, Edit slug | LocaleFrame{s:{v:"seo",x:""}} | 1440, 390 | Journal |
+| loc.slug.published | Edit slug | Published version: warning about old links | LocaleFrame{s:{v:"seo",x:"editSlug"}} | 1440, 390 | Journal |
+| loc.url.unset | Public URL not configured | No pattern, no fabricated URL | LocaleFrame{s:{v:"seo",x:"unset"}} | 1440, 390 | Journal |
+| loc.l10.noSocial | Social locale not set | fr has no region and none is set: og:locale omitted | LocaleFrame{s:{v:"seo",x:"noSocial"}} | 1440, 390 | Journal |
+| loc.l10.api | Integration: languages | Exact lookup, resolve by article group, errors | LocaleFrame{s:{v:"api",x:""}} | 1440, 390 | Journal |