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/i18n/translations.ts

@@ -656,6 +656,7 @@ export interface Translations {
     widgetShowRatingDesc: string;
     widgetShowPriceDesc: string;
     widgetJsonDesc: string;
+    widgetJsonInvalid: string;
     wishlistFeatureDesc: string;
     compareFeatureDesc: string;
     reviewsFeatureDesc: string;