feat(project-editor): reusable image-field (thumbnail+replace+remove), branding OG image+gallery

- shared app-image-field component: thumbnail preview, replace, remove, opens media-picker
- branding: add socialImageUrl + galleryUrls fields, wire to new image-field
- footer: logo + payment icon fields use image-field (drop manual media-picker plumbing)
- i18n: common.remove, adminCategories.replaceImage, builder.socialImage/gallery keys (en/ru/hy)

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

src/app/shared/models/config/branding.model.ts

@@ -8,6 +8,8 @@ export interface BrandingConfig {
   logoCompactUrl?: UrlString;
   faviconUrl: UrlString;
   appIconUrl?: UrlString;
+  socialImageUrl?: UrlString;
+  galleryUrls?: UrlString[];
   supportEmail?: string;
   supportPhone?: string;
 }