feat(builder): mobile-B touch editing -- selection toolbar, tap-to-add, swipe-dismiss

Phase B makes the Craft.js editor genuinely usable by touch on top of Phase
A's responsive shell, gated entirely behind useIsMobile()/<=768px:

- Extract useNodeActions(nodeId) out of ContextMenu.tsx (move/duplicate/
  delete/select-parent), shared by the desktop right-click menu (behavior
  unchanged) and the new mobile MobileSelectionToolbar.
- MobileSelectionToolbar: bottom-fixed selection toolbar (Move Up/Down,
  Duplicate, Select Parent, Edit Styles, two-tap Delete confirm), hidden
  while a sheet is open.
- BlocksPanel: tap-to-add on mobile (insert after selection, close sheet,
  select + scroll the new node into view); desktop drag/double-click
  unchanged.
- LayersPanel rows >=44px on mobile; HeadCodeModal portaled to document.body
  (same fix TemplateModal already had); BottomSheet gets swipe-to-dismiss
  and on-screen-keyboard clearance via a new useVisualViewportInsets hook.

Also fixes two pre-existing bugs surfaced only by driving a real Craft.js
document with Playwright touch input (masked by tests that mock
@craftjs/core): regenerateTreeIds structuredClone'd a live node's whole
data object, including the component function reference in data.type,
throwing DataCloneError and silently breaking Duplicate/Paste for every
node type; and an earlier useNodeActions draft cached canMoveUp/canMoveDown
inside a useEditor collector closed over nodeId, which goes stale for one
render whenever the selection changes without an unrelated store event.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

craft/src/editor/EditorShell.tsx

@@ -4,6 +4,7 @@ import { TopBar } from '../panels/topbar/TopBar';
 import { LeftPanel } from '../panels/left/LeftPanel';
 import { RightPanel } from '../panels/right/RightPanel';
 import { MobilePanelBar } from '../panels/mobile/MobilePanelBar';
+import { MobileSelectionToolbar } from '../panels/mobile/MobileSelectionToolbar';
 import { Canvas } from './Canvas';
 import { ContextMenu } from '../panels/context-menu/ContextMenu';
 import { useContextMenu } from '../hooks/useContextMenu';
@@ -97,6 +98,7 @@ export const EditorShell: React.FC = () => {
           {!isMobile && <RightPanel />}
         </div>
         {isMobile && <MobilePanelBar />}
+        {isMobile && <MobileSelectionToolbar />}
         <ContextMenu
           visible={menuState.visible}
           x={menuState.x}