fix(widgets): stop silently discarding invalid JSON edits in the props fallback textarea

updateJson() caught JSON.parse failures and did nothing, but the textarea
was bound to propsJson(committed props) - so on the next change-detection
pass, any in-progress invalid edit snapped back to the last-saved value
with zero feedback. Verified live via window.ng.getComponent(): typing
invalid JSON now keeps the user's draft on screen with an inline error;
fixing it commits and clears the draft/error.

Also: homepage-section drop() used CdkDragDrop<any[]> - switched to
unknown[] per the no-any rule, no behavior change.

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

src/app/features/project-editor/sections/homepage-section.component.ts

@@ -44,7 +44,7 @@ export class ProjectEditorHomepageSectionComponent {
     return this.layoutStrategyOptions.find(option => option.value === strategy)?.descKey ?? '';
   }
 
-  drop(event: CdkDragDrop<any[]>): void {
+  drop(event: CdkDragDrop<unknown[]>): void {
     const sections = [...this.sections()];
     moveItemInArray(sections, event.previousIndex, event.currentIndex);
     this.facade.updateBootstrap(current => ({