feat(builder): visual footer builder with drag-and-drop columns

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

P0 user feedback: footer static pages were comma-separated text; no way to add extra phones/emails for different countries.

- New FooterColumnConfig/FooterLinkConfig model (footer-config.model.ts): columns of links, each link pointing at an existing static page (resolved by key, so it survives route renames) or a custom URL
- Footer Builder UI: add/remove columns and links, per-link toggle between 'existing page' (dropdown of real static pages) and 'custom URL', drag-and-drop reordering of both columns and links via @angular/cdk/drag-drop (same primitive already used by the homepage section builder)
- Wired FooterResolverService (the service the real storefront footer actually renders through) to read footer.columns as the primary source when present - without this the builder would have saved data nobody ever displayed. Falls back to the existing legacy static-page auto-grouping when no columns are configured, so existing sites are unaffected
- CompanyContactConfig gains additionalPhones/additionalEmails (primary phone/email field unchanged) with add/remove UI for country-specific support lines
- Old comma-separated staticPageKeys input removed from the UI; field kept on the model as deprecated/read-compat only
- New builder.* i18n keys (en/ru/hy); fixed an accidental duplicate-key collision with pre-existing navigation-section addLink/removeLink keys during the rename pass
- Verified in browser: added column, added link, switched link source page->custom, added phone number - all reactive and error-free

src/app/i18n/en.ts

@@ -634,6 +634,24 @@ export const en: Translations = {
     iconAltLabelDesc: 'Alt text describing the payment icon for accessibility.',
     socialLinkUrlDesc: 'Full URL to the social media profile, must start with http:// or https://.',
     staticPagesFieldDesc: 'Static pages (about, terms, privacy, etc.) linked from the footer.',
+    additionalPhones: 'Extra phone numbers',
+    additionalPhonesDesc: 'Add more numbers if you support customers in different countries.',
+    addPhone: 'Add phone number',
+    removePhone: 'Remove phone number',
+    additionalEmails: 'Extra email addresses',
+    additionalEmailsDesc: 'Add more addresses for different regions or departments.',
+    addEmail: 'Add email address',
+    removeEmail: 'Remove email address',
+    footerColumns: 'Footer columns',
+    footerColumnsDesc: 'Group links into columns, like a real footer. Drag columns and links to reorder them.',
+    footerColumnTitlePlaceholder: 'Column title, e.g. Company',
+    footerLinkLabelPlaceholder: 'Link text',
+    footerLinkExistingPage: 'Existing page',
+    footerLinkCustomUrl: 'Custom URL',
+    addColumn: 'Add column',
+    removeColumn: 'Remove column',
+    addColumnLink: 'Add link',
+    removeColumnLink: 'Remove link',
     sectionVisibleDesc: 'Whether this homepage section is shown to shoppers.',
     layoutStrategyLabel: 'Layout strategy',
     layoutStrategyDesc: 'How widgets inside this section are arranged.',