feat(project-editor): finish field descriptions + enum dropdowns across all sections

Wires up the remaining editor sections (theme, header, footer, homepage,
widgets, features, languages, navigation) with the description text and
dropdown UX started for General/Branding:

- Every enum-backed field is now a <select> with a description per option,
  not free text: theme.mode, the new site-wide layout.type (previously had
  no editor at all - added to the Theme section, and added to that
  section's reset-scope), homepage section layout.strategy, and
  catalog.navigationMode (also previously unedited, added to Features).
- Every other field (colors, header toggles, footer contact/company fields,
  widget props, feature flags, language add, nav link label/url/visible)
  gets a one-line plain-language description under its label via the new
  *Desc i18n keys (en/ru/hy) prepared earlier.
- Genuinely open text (widget layout variant strings, JSON props) stays
  free text, description-only, per the existing widgetLayoutDesc/widgetJsonDesc
  wording - not force-fit into a dropdown.

Verified: tsc --noEmit and ng build both clean.

src/app/features/project-editor/sections/homepage-section.component.ts

@@ -4,6 +4,12 @@ import { FormsModule } from '@angular/forms';
 import { ProjectEditorFacade } from '../facade/project-editor.facade';
 import { TranslatePipe } from '../../../i18n/translate.pipe';
 
+export interface LayoutStrategyOption {
+  value: 'stack' | 'grid' | 'hero' | 'carousel' | 'split';
+  labelKey: string;
+  descKey: string;
+}
+
 @Component({
   selector: 'app-project-editor-homepage-section',
   standalone: true,
@@ -17,6 +23,18 @@ export class ProjectEditorHomepageSectionComponent {
   readonly homePage = this.facade.homepagePage;
   readonly sections = computed(() => [...(this.homePage()?.sections ?? [])].sort((a, b) => a.order - b.order));
 
+  readonly layoutStrategyOptions: LayoutStrategyOption[] = [
+    { value: 'stack', labelKey: 'builder.layoutStrategyStack', descKey: 'builder.layoutStrategyStackDesc' },
+    { value: 'grid', labelKey: 'builder.layoutStrategyGrid', descKey: 'builder.layoutStrategyGridDesc' },
+    { value: 'hero', labelKey: 'builder.layoutStrategyHero', descKey: 'builder.layoutStrategyHeroDesc' },
+    { value: 'carousel', labelKey: 'builder.layoutStrategyCarousel', descKey: 'builder.layoutStrategyCarouselDesc' },
+    { value: 'split', labelKey: 'builder.layoutStrategySplit', descKey: 'builder.layoutStrategySplitDesc' },
+  ];
+
+  layoutStrategyDescKey(strategy: string | undefined): string {
+    return this.layoutStrategyOptions.find(option => option.value === strategy)?.descKey ?? '';
+  }
+
   drop(event: CdkDragDrop<any[]>): void {
     const sections = [...this.sections()];
     moveItemInArray(sections, event.previousIndex, event.currentIndex);