Implement collection item reordering with bulk operations and persistent HTML attributes

- Add bulk reorder API endpoint (PUT /api/collections/{id}/reorder) with atomic transactions
- Replace individual position updates with efficient bulk operations in frontend
- Implement unified ID generation and proper data-item-id injection during enhancement
- Fix collection item position persistence through content edit cycles
- Add optimistic UI with rollback capability for better user experience
- Update sqlc queries to include last_edited_by fields in position updates
- Remove obsolete data-content-type attributes and unify naming conventions

lib/src/core/api-client.js

@@ -243,21 +243,19 @@ export class ApiClient {
     }
 
     /**
-     * Update collection item position (for reordering)
+     * Reorder collection items in bulk
      * @param {string} collectionId - Collection ID
-     * @param {string} itemId - Item ID to update
-     * @param {number} newPosition - New position index
+     * @param {Array} itemOrder - Array of {itemId, position} objects
      * @returns {Promise<boolean>} Success status
      */
-    async updateCollectionItemPosition(collectionId, itemId, newPosition) {
+    async reorderCollection(collectionId, itemOrder) {
         try {
             const collectionsUrl = this.getCollectionsUrl();
             const payload = {
-                site_id: this.siteId,
-                position: newPosition
+                items: itemOrder
             };
 
-            const response = await fetch(`${collectionsUrl}/${collectionId}/items/${itemId}`, {
+            const response = await fetch(`${collectionsUrl}/${collectionId}/reorder?site_id=${this.siteId}`, {
                 method: 'PUT',
                 headers: {
                     'Content-Type': 'application/json',
@@ -270,11 +268,11 @@ export class ApiClient {
                 return true;
             } else {
                 const errorText = await response.text();
-                console.error(`❌ Failed to update collection item position (${response.status}): ${errorText}`);
+                console.error(`❌ Failed to reorder collection (${response.status}): ${errorText}`);
                 return false;
             }
         } catch (error) {
-            console.error('❌ Error updating collection item position:', error);
+            console.error('❌ Error reordering collection:', error);
             return false;
         }
     }