fix(global-sections): block structural edits inside a global-section instance

syncInstances rebuilds an instance's subtree from the master, so a node
dropped, pasted, duplicated or moved into an instance vanished from every page
on the next master edit. Chosen approach: BLOCK (not preserve-on-sync):
- every resolver component's Craft canMoveIn/canMoveOut refuses a canvas inside
  an instance (canvas DnD, Layers DnD, actions.move); synthetic shell-inner
  nodes now carry the component's rules instead of hardcoded allow-all
- insertBlock (BlocksPanel / EmptyContainerAdd / palette), paste (menu +
  shortcut), duplicate (menu + shortcut) and Sitesmith patch/section replace
  redirect to after the instance or refuse; no empty-container '+' inside one
The instance root still moves/duplicates as a whole; content overrides are
unchanged.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

craft/src/components/resolver.ts

@@ -41,6 +41,7 @@ import { OpeningHours } from './business/OpeningHours';
 import { StickyCallBar } from './business/StickyCallBar';
 import { ReviewsStrip } from './business/ReviewsStrip';
 import { BookingEmbed } from './business/BookingEmbed';
+import { canvasInInstance } from '../utils/global-sections';
 
 export const componentResolver = {
   Container,
@@ -87,3 +88,27 @@ export const componentResolver = {
   ReviewsStrip,
   BookingEmbed,
 };
+
+/**
+ * #57 finding 4: no drop / move / reorder into, inside or out of a global
+ * section instance (its structure is rebuilt from the master on every sync).
+ * Wraps every component's Craft `canMoveIn` / `canMoveOut` -- the rules
+ * Craft's `isDroppable` checks for canvas DnD, Layers DnD and
+ * `actions.move` -- keeping each component's own rule.
+ */
+type RuleFn = (nodes: any, self: any, helper: any) => boolean;
+for (const comp of Object.values(componentResolver) as any[]) {
+  const craft = (comp.craft ??= {});
+  const rules = craft.rules ?? {};
+  if (rules.__instanceGuard) continue;
+  const prevIn: RuleFn | undefined = rules.canMoveIn;
+  const prevOut: RuleFn | undefined = rules.canMoveOut;
+  craft.rules = {
+    ...rules,
+    canMoveIn: (incoming: any, self: any, helper: any) =>
+      !canvasInInstance(self, helper) && (prevIn ? prevIn(incoming, self, helper) : true),
+    canMoveOut: (outgoing: any, self: any, helper: any) =>
+      !canvasInInstance(self, helper) && (prevOut ? prevOut(outgoing, self, helper) : true),
+    __instanceGuard: true,
+  };
+}