ContentPage.seo (title/description/keywords/canonical/ogTitle/ogDescription/
ogImage) was already modeled and serialized to bootstrap JSON but had no
editable UI. Added updateSeo() to the component and a translated SEO fieldset
using app-form-field/app-input. Added seoSection/seoTitle/seoDescription/
seoKeywords/seoCanonical/seoOgTitle/seoOgDescription/seoOgImage translation
keys to en/ru/hy and the Translations type.
Verified in browser at /edit/static-pages: SEO section renders with
translated labels for all three mock pages.
Replace raw button/input elements with app-button, app-input, app-card,
app-form-field, app-badge, app-empty-state across the static pages CMS editor.
Checkboxes left native (no checkbox primitive built yet).
Also fix pre-existing bug in ContentPageService.normalizePages: iterating
Object.values(config) lost the record key, so legacy-shaped bootstrap entries
without explicit id/slug fields (e.g. mock bootstrap.json's about-us,
privacy-policy, terms-of-service) crashed normalizeSlug(undefined). Now
falls back to the record key for id/slug/title.
Verified in browser at /edit/static-pages: renders correctly, primitives
styled per tenant CSS vars, no console errors after fix.
