fix(cms): reindex nested array paths correctly in Content Editor

reindexItems replaced the FIRST [n] index in a data-path, which for nested
arrays (e.g. services[1].specs.items) rewrote the OUTER array index instead
of the item's own index. Deleting or adding an item scattered paths across
services[0..n], produced sparse arrays (null items) and schema errors like
'$.details.services[1].specs.items[0]: string érték szükséges'.

Rewrite only the index directly following the reindexed array's path prefix;
drop the now-redundant str-item special case.

Closes MITHOME-30

content-editor.js

@@ -298,21 +298,23 @@ function makeObjCard(obj, idx, path) {
 function reindexItems(itemsEl) {
   if (!itemsEl) return;
   const path = itemsEl.dataset.arrayItems;
+  // WHY: rewrite only the index that directly follows THIS array's own path prefix.
+  // A generic "replace first [n]" rule corrupts nested arrays (e.g. deleting from
+  // services[1].specs.items rewrites the OUTER services index and scatters paths
+  // across services[0..n], producing sparse arrays and schema errors).
+  const prefix = path + '[';
   Array.from(itemsEl.children).forEach((child, i) => {
-    // Update all data-path in this child
     child.querySelectorAll('[data-path]').forEach(el => {
       const old = el.dataset.path;
-      // Replace the array index part: path[old_i] → path[new_i]
-      el.dataset.path = old.replace(/^(.+?)\[(\d+)\]/, (_,p) => p + '[' + i + ']');
+      if (typeof old !== 'string' || !old.startsWith(prefix)) return;
+      const rest = old.slice(prefix.length);
+      const bracketEnd = rest.indexOf(']');
+      const suffix = bracketEnd === -1 ? '' : rest.slice(bracketEnd);
+      el.dataset.path = prefix + i + suffix;
     });
     // Update card header
     const hdr = child.querySelector('.card-header');
     if (hdr) hdr.textContent = path + '[' + i + ']';
-    // Update str-item textarea
-    const ta = child.querySelector('textarea[data-path]');
-    if (ta && !ta.closest('.obj-card')) {
-      ta.dataset.path = path + '[' + i + ']';
-    }
   });
 }