feat(builder): redesign marketplace builder experience and navigation

Renamed the experience consistently to Marketplace Builder everywhere
visible (page title/subtitle, breadcrumbs, sidebar, dashboard quick
action/shortcut copy) - internal ProjectEditor class/selector names
kept as-is to avoid regressions. builder.title/subtitle no longer say
'bootstrap-config editing surface' to end users.

New business-oriented IA (builder-groups.model.ts): 12 existing
ProjectEditorSectionIds regrouped into 8 groups (Marketplace, Branding
and Design, Homepage, Content, Languages, Marketplace Features,
Navigation and Search, Preview) - every existing section mapped to
exactly one group, none dropped, no group points at a page that
doesn't exist.

New Builder landing page at /edit (was a redirect straight into the
General form): readiness percent, recommended next step, one overview
card per group (purpose + real complete/in-progress/not-started/unknown
status, icon+text never color-alone), a Marketplace Readiness
checklist, quick links. All derived from real facade/schema signals
(required-field fill state, modifiedSections, staticPages, catalog
counts via BackofficeDataService) or explicitly marked unknown
(the "preview reviewed" check has no tracking - shown as unknown,
never guessed).

Section pages (/edit/:section) now share one consistent header:
breadcrumb (Builder > Group > Section), draft/published + modified
badges, and a contextual help panel (what is this / where visible /
what happens if you skip it) sourced per group. Sidebar nav rewritten
as grouped, icon-led sections with per-section and per-group status
indicators; layout converted from a top pill-tab bar to a responsive
sidebar (desktop 280px, tablet 72px icon rail, mobile drawer with
Escape-to-close), matching the Sprint 1 admin shell pattern. Section
form components themselves untouched.

Routes: 'edit' is now its own landing route instead of redirecting to
'edit/general'; /builder and /project-editor redirect to 'edit'.
Sprint 1/2 destinations that pointed at edit/general now point at the
new edit landing page.

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

src/app/features/admin/dashboard/facade/admin-dashboard.facade.ts

@@ -18,7 +18,7 @@ import {
 const QUICK_ACTIONS: AdminDashboardQuickAction[] = [
   { id: 'add-product', icon: 'pi-plus-circle', labelKey: 'dashboard.actionAddProduct', descriptionKey: 'dashboard.actionAddProductDescription', route: ['backoffice', 'products', 'create'] },
   { id: 'create-category', icon: 'pi-sitemap', labelKey: 'dashboard.actionCreateCategory', descriptionKey: 'dashboard.actionCreateCategoryDescription', route: ['backoffice', 'categories', 'create'] },
-  { id: 'edit-project', icon: 'pi-th-large', labelKey: 'dashboard.actionEditProject', descriptionKey: 'dashboard.actionEditProjectDescription', route: ['edit', 'general'] },
+  { id: 'edit-project', icon: 'pi-th-large', labelKey: 'dashboard.actionEditProject', descriptionKey: 'dashboard.actionEditProjectDescription', route: ['edit'] },
   { id: 'edit-homepage', icon: 'pi-home', labelKey: 'dashboard.actionEditHomepage', descriptionKey: 'dashboard.actionEditHomepageDescription', route: ['edit', 'homepage'] },
   { id: 'media-library', icon: 'pi-images', labelKey: 'dashboard.actionMediaLibrary', descriptionKey: 'dashboard.actionMediaLibraryDescription', route: ['backoffice', 'media'] },
   { id: 'orders', icon: 'pi-shopping-cart', labelKey: 'dashboard.actionOrders', descriptionKey: 'dashboard.actionOrdersDescription', route: ['backoffice', 'orders'] },
@@ -27,7 +27,7 @@ const QUICK_ACTIONS: AdminDashboardQuickAction[] = [
 const SHORTCUTS: AdminDashboardShortcut[] = [
   { id: 'products', icon: 'pi-box', labelKey: 'dashboard.actionProducts', route: ['backoffice', 'products'] },
   { id: 'categories', icon: 'pi-tags', labelKey: 'dashboard.actionCategories', route: ['backoffice', 'categories'] },
-  { id: 'marketplace-builder', icon: 'pi-sitemap', labelKey: 'dashboard.shortcutMarketplaceBuilder', route: ['edit', 'general'] },
+  { id: 'marketplace-builder', icon: 'pi-sitemap', labelKey: 'dashboard.shortcutMarketplaceBuilder', route: ['edit'] },
   { id: 'static-pages', icon: 'pi-file-edit', labelKey: 'dashboard.actionStaticPages', route: ['backoffice', 'static-pages'] },
   { id: 'orders', icon: 'pi-shopping-cart', labelKey: 'dashboard.actionOrders', route: ['backoffice', 'orders'] },
   { id: 'users', icon: 'pi-users', labelKey: 'dashboard.actionUsers', route: ['backoffice', 'users'] },