fix: only show popup when clicking inside page template

Filter clicks to only trigger ElementPopup for elements inside
.pagedjs_page, preventing popups from appearing when clicking
on wrapper elements like .pagedjs_pages.

Also adds lock/unlock SVG icons.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/App.vue

@@ -91,8 +91,9 @@ const handleIframeClick = (event) => {
     return;
   }
 
-  // Otherwise handle as element click
-  if (element.tagName === 'BODY' || element.tagName === 'HTML') {
+  // Only show popup for elements inside the page template
+  const isInsidePage = element.closest('.pagedjs_page');
+  if (!isInsidePage) {
     elementPopup.value.close();
     pagePopup.value.close();
     return;