fix: backup close button is now a STATIC element in overlay (never replaced by innerHTML)

- Close button created once in createOverlay() as a static DOM element
  outside the panel, positioned absolutely (top-right corner)
- Never touched by setBody() innerHTML replacements
- Uses same class/id pattern as Graph View: editor-btn + backup-close
- Handler attached via addEventListener ONCE, never needs re-binding
- Removed all CLOSE_BTN from render functions (loading/error/empty/main)

frontend/js/backups.js

@@ -83,6 +83,19 @@ function createOverlay() {
   panel.id = 'backup-viewer-panel';
   overlay.appendChild(panel);
 
+  // Close button OUTSIDE the panel — never touched by innerHTML, always present
+  const closeBtn = document.createElement('button');
+  closeBtn.className = 'editor-btn backup-close-btn';
+  closeBtn.id = 'backup-close';
+  closeBtn.title = 'Fermer';
+  closeBtn.style.cssText = 'position:absolute;top:12px;right:12px;z-index:1002;flex-shrink:0';
+  closeBtn.innerHTML = '<i data-lucide="x" style="width:15px;height:15px"></i>';
+  closeBtn.addEventListener('click', (e) => {
+    e.stopPropagation();
+    close();
+  });
+  overlay.appendChild(closeBtn);
+
   // Keyboard: Escape closes the viewer
   _escHandler = (e) => {
     if (e.key === 'Escape' && state.overlay) close();
@@ -92,20 +105,10 @@ function createOverlay() {
   return overlay;
 }
 
-/** Replace panel content and re-bind the close button. */
+/** Replace panel content. Close button is static in the overlay, never replaced. */
 function setBody(html) {
   const panel = document.getElementById('backup-viewer-panel');
-  if (!panel) return;
-  panel.innerHTML = html;
-  safeCreateIcons();
-  // Bind close button — same pattern as AdminPanel
-  const closeBtn = panel.querySelector('.backup-close-btn');
-  if (closeBtn) {
-    closeBtn.addEventListener('click', (e) => {
-      e.stopPropagation();
-      close();
-    });
-  }
+  if (panel) panel.innerHTML = html;
 }
 
 let _escHandler = null;
@@ -127,14 +130,10 @@ function close() {
 // Rendering
 // ---------------------------------------------------------------------------
 
-/** Close button HTML — same pattern as AdminPanel editor-btn */
-const CLOSE_BTN = '<button class="backup-close-btn" title="Fermer"><i data-lucide="x" style="width:16px;height:16px"></i></button>';
-
 function renderLoading() {
   return `
     <div class="backup-header">
       <h3>Backups</h3>
-      ${CLOSE_BTN}
     </div>
     <div class="backup-body">
       <div class="tree-loading" style="padding:2rem;text-align:center">
@@ -145,10 +144,9 @@ function renderLoading() {
 }
 
 function renderError(msg) {
-  return `
+  return \`
     <div class="backup-header">
       <h3>Backups</h3>
-      ${CLOSE_BTN}
     </div>
     <div class="backup-body" style="text-align:center;padding:2rem;color:var(--text-muted)">
       <p>${escapeHtml(msg)}</p>
@@ -156,10 +154,9 @@ function renderError(msg) {
 }
 
 function renderEmpty() {
-  return `
+  return \`
     <div class="backup-header">
-      <h3>Backups — ${escapeHtml(state.path)}</h3>
-      ${CLOSE_BTN}
+      <h3>Backups — \${escapeHtml(state.path)}</h3>
     </div>
     <div class="backup-body" style="text-align:center;padding:2rem;color:var(--text-muted)">
       <p>Aucun backup disponible pour ce fichier.</p>
@@ -189,8 +186,7 @@ function renderMainView() {
         <span class="backup-file-path">${escapeHtml(state.path)}</span>
       </div>
       <div class="backup-header-right">
-        <span class="backup-count">${b.length} backup${b.length > 1 ? 's' : ''}</span>
-        ${CLOSE_BTN}
+        <span class="backup-count">\${b.length} backup\${b.length > 1 ? 's' : ''}</span>
       </div>
     </div>