feat: add page template interaction with PagePopup

Implements page edge hover detection and click handling:
- Hover near page edges (30px threshold) shows light outline
- Click on page edge opens PagePopup for template customization
- PagePopup component similar to ElementPopup but for @page rules
- Both popups coordinate to show only one at a time

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

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

src/App.vue

@@ -2,6 +2,7 @@
 import PagedJsWrapper from './components/PagedJsWrapper.vue';
 import EditorPanel from './components/editor/EditorPanel.vue';
 import ElementPopup from './components/ElementPopup.vue';
+import PagePopup from './components/PagePopup.vue';
 import PreviewLoader from './components/PreviewLoader.vue';
 import { onMounted, ref, watch, computed, provide } from 'vue';
 import { useStylesheetStore } from './stores/stylesheet';
@@ -11,10 +12,15 @@ const stylesheetStore = useStylesheetStore();
 const previewFrame1 = ref(null);
 const previewFrame2 = ref(null);
 const elementPopup = ref(null);
+const pagePopup = ref(null);
 const activeTab = ref('');
 
 provide('activeTab', activeTab);
 
+// Page interaction state
+const hoveredPage = ref(null);
+const EDGE_THRESHOLD = 30; // px from edge to trigger hover
+
 let savedScrollPercentage = 0;
 const currentFrameIndex = ref(1); // 1 or 2, which iframe is currently visible
 const isTransitioning = ref(false);
@@ -25,6 +31,77 @@ const activeFrame = computed(() => {
     : previewFrame2.value;
 });
 
+// Check if mouse position is near the edges of a page element
+const isNearPageEdge = (pageElement, mouseX, mouseY) => {
+  const rect = pageElement.getBoundingClientRect();
+
+  const nearLeft = mouseX >= rect.left && mouseX <= rect.left + EDGE_THRESHOLD;
+  const nearRight = mouseX >= rect.right - EDGE_THRESHOLD && mouseX <= rect.right;
+  const nearTop = mouseY >= rect.top && mouseY <= rect.top + EDGE_THRESHOLD;
+  const nearBottom = mouseY >= rect.bottom - EDGE_THRESHOLD && mouseY <= rect.bottom;
+
+  const inHorizontalRange = mouseY >= rect.top && mouseY <= rect.bottom;
+  const inVerticalRange = mouseX >= rect.left && mouseX <= rect.right;
+
+  return (
+    (nearLeft && inHorizontalRange) ||
+    (nearRight && inHorizontalRange) ||
+    (nearTop && inVerticalRange) ||
+    (nearBottom && inVerticalRange)
+  );
+};
+
+// Handle mouse movement in iframe
+const handleIframeMouseMove = (event) => {
+  const pages = event.target.ownerDocument.querySelectorAll('.pagedjs_page');
+  let foundPage = null;
+
+  for (const page of pages) {
+    if (isNearPageEdge(page, event.clientX, event.clientY)) {
+      foundPage = page;
+      break;
+    }
+  }
+
+  // Update hover state
+  if (foundPage !== hoveredPage.value) {
+    // Remove highlight from previous page
+    if (hoveredPage.value) {
+      hoveredPage.value.style.outline = '';
+    }
+
+    // Add highlight to new page
+    if (foundPage) {
+      foundPage.style.outline = '2px solid rgba(97, 175, 239, 0.3)';
+    }
+
+    hoveredPage.value = foundPage;
+  }
+};
+
+// Handle click in iframe
+const handleIframeClick = (event) => {
+  const element = event.target;
+
+  // Check if clicking near a page edge
+  if (hoveredPage.value) {
+    event.stopPropagation();
+    pagePopup.value.open(hoveredPage.value);
+    elementPopup.value.close();
+    return;
+  }
+
+  // Otherwise handle as element click
+  if (element.tagName === 'BODY' || element.tagName === 'HTML') {
+    elementPopup.value.close();
+    pagePopup.value.close();
+    return;
+  }
+
+  elementPopup.value.handleIframeClick(event);
+  pagePopup.value.close();
+};
+
 const renderPreview = async (shouldReloadFromFile = false) => {
   if (isTransitioning.value) return;
   isTransitioning.value = true;
@@ -73,10 +150,9 @@ const renderPreview = async (shouldReloadFromFile = false) => {
   `;
 
   hiddenFrame.onload = () => {
-    hiddenFrame.contentDocument.addEventListener(
-      'click',
-      elementPopup.value.handleIframeClick
-    );
+    // Add event listeners for page and element interactions
+    hiddenFrame.contentDocument.addEventListener('mousemove', handleIframeMouseMove);
+    hiddenFrame.contentDocument.addEventListener('click', handleIframeClick);
 
     // Close Coloris when clicking in the iframe
     hiddenFrame.contentDocument.addEventListener('click', () => {
@@ -151,6 +227,7 @@ onMounted(() => renderPreview(true));
   <PreviewLoader :isLoading="isTransitioning" :shifted="activeTab.length > 0" />
 
   <ElementPopup ref="elementPopup" :iframeRef="activeFrame" />
+  <PagePopup ref="pagePopup" :iframeRef="activeFrame" />
 </template>
 
 <style>
@@ -168,9 +245,9 @@ onMounted(() => renderPreview(true));
 }
 
 .preview-frame.shifted {
-  margin-left: 19rem;
-  transform: scale(0.7) translateY(-30vh);
-  height: 142vh;
+  margin-left: 17.55rem;
+  transform: scale(0.65) translateY(-40vh);
+  height: 155vh;
 }
 
 .preview-frame:nth-of-type(1) {