fix(icons): migrate Marketplace Builder to Lucide

Replace every PrimeIcons pi-* usage across the builder: overview page
(back link, next-step arrow, section cards, readiness checklist,
quick links), sidebar nav (group/section status dots), main layout
(back/home/menu/help icons), brand + homepage overview panels
(checklist ok/pending dots, contrast warning), footer/homepage/widgets
section editors (drag handles, move up/down, duplicate, remove), and
the HTML editor toolbar (list/link/image/table/divider/code/embed).

Notable correctness fix: PrimeIcons reused pi-bars for both the
hamburger menu toggle AND every drag handle - two different meanings
sharing one icon (exactly the kind of icon collision the audit calls
out). Added a dedicated 'grip' icon (GripVertical) for drag handles so
menu and drag-to-reorder are visually distinct.

Added a global .spin utility (icon-registry has no built-in spinner
animation) for the one loading-spinner icon in the builder overview
checklist.

All icon-bearing fields (BuilderGroup.icon, BlockCatalogEntry.icon,
WIDGET_ICONS, STATUS_ICON, HtmlEditorToolbarCommand.icon, etc.) are
now typed AppIconName instead of string.

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

src/app/shared/ui/icon/icon-registry.ts

@@ -29,6 +29,7 @@ import {
   LucideFlag as Flag,
   LucideFolder as Folder,
   LucideGlobe as Globe,
+  LucideGripVertical as GripVertical,
   LucideHeart as Heart,
   LucideHelpCircle as HelpCircle,
   LucideHistory as History,
@@ -144,6 +145,7 @@ export const APP_ICONS = {
   creditCard: CreditCard,
   flag: Flag,
   globe: Globe,
+  grip: GripVertical,
   history: History,
   link: Link,
   list: List,