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/app.routes.ts

@@ -43,6 +43,10 @@ const coreRoutes: Routes = [
     path: 'search',
     loadComponent: () => import('./features/website/catalog/containers/catalog-container.component').then(m => m.CatalogContainerComponent)
   },
+  {
+    path: 'edit',
+    loadComponent: () => import('./features/project-editor/pages/builder-overview-page.component').then(m => m.BuilderOverviewPageComponent)
+  },
   {
     path: 'edit/:section',
     loadComponent: () => import('./features/project-editor/pages/project-editor-page.component').then(m => m.ProjectEditorPageComponent),
@@ -202,19 +206,14 @@ const coreRoutes: Routes = [
       { path: '**', redirectTo: 'dashboard' }
     ]
   },
-  {
-    path: 'edit',
-    redirectTo: 'edit/general',
-    pathMatch: 'full'
-  },
   {
     path: 'builder',
-    redirectTo: 'edit/general',
+    redirectTo: 'edit',
     pathMatch: 'full'
   },
   {
     path: 'project-editor',
-    redirectTo: 'edit/general',
+    redirectTo: 'edit',
     pathMatch: 'full'
   },
   {