Auto-enable dev mode when Joomla debug is on; fix TOC heading detection

- Development mode now activates automatically when Joomla global
  debug is enabled, so admins don't need to toggle both settings.
- Bootstrap TOC now detects the highest heading level present (even
  if only one exists) and includes up to two levels below it
  (e.g. h2 → h2, h3, h4). Fixes incorrect top-level detection and
  adds proper three-level nesting support.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/media/vendor/bootstrap-toc/bootstrap-toc.js

@@ -83,11 +83,12 @@
         return this.generateNavEl(anchor, text);
       },
 
-      // Find the first heading level (`<h1>`, then `<h2>`, etc.) that has more than one element. Defaults to 1 (for `<h1>`).
+      // Find the highest (lowest-numbered) heading level present in the scope.
+      // Returns the tag number of the first heading found (e.g. 2 for <h2>).
       getTopLevel: function($scope) {
         for (var i = 1; i <= 6; i++) {
           var $headings = this.findOrFilter($scope, 'h' + i);
-          if ($headings.length > 1) {
+          if ($headings.length >= 1) {
             return i;
           }
         }
@@ -95,14 +96,15 @@
         return 1;
       },
 
-      // returns the elements for the top level, and the next below it
+      // Returns elements for the top level and up to two levels below it.
+      // e.g. if topLevel is 2 → h2, h3, h4
       getHeadings: function($scope, topLevel) {
-        var topSelector = 'h' + topLevel;
+        var selectors = [];
+        for (var i = topLevel; i <= Math.min(topLevel + 2, 6); i++) {
+          selectors.push('h' + i);
+        }
 
-        var secondaryLevel = topLevel + 1;
-        var secondarySelector = 'h' + secondaryLevel;
-
-        return this.findOrFilter($scope, topSelector + ',' + secondarySelector);
+        return this.findOrFilter($scope, selectors.join(','));
       },
 
       getNavLevel: function(el) {
@@ -110,26 +112,38 @@
       },
 
       populateNav: function($topContext, topLevel, $headings) {
-        var $context = $topContext;
-        var $prevNav;
+        var $contexts = {};
+        $contexts[topLevel] = $topContext;
+        var $prevNavByLevel = {};
 
         var helpers = this;
         $headings.each(function(i, el) {
           var $newNav = helpers.generateNavItem(el);
           var navLevel = helpers.getNavLevel(el);
 
-          // determine the proper $context
           if (navLevel === topLevel) {
-            // use top level
-            $context = $topContext;
-          } else if ($prevNav && $context === $topContext) {
-            // create a new level of the tree and switch to it
-            $context = helpers.createChildNavList($prevNav);
-          } // else use the current $context
-
-          $context.append($newNav);
-
-          $prevNav = $newNav;
+            // Top level — append directly
+            $topContext.append($newNav);
+            $prevNavByLevel = {};
+            $prevNavByLevel[topLevel] = $newNav;
+            // Reset deeper contexts so next child creates a fresh sublist
+            $contexts = {};
+            $contexts[topLevel] = $topContext;
+          } else {
+            // Child level — ensure parent context exists
+            var parentLevel = navLevel - 1;
+            if (!$contexts[navLevel] && $prevNavByLevel[parentLevel]) {
+              $contexts[navLevel] = helpers.createChildNavList($prevNavByLevel[parentLevel]);
+            }
+            var $ctx = $contexts[navLevel] || $topContext;
+            $ctx.append($newNav);
+            $prevNavByLevel[navLevel] = $newNav;
+            // Reset deeper contexts
+            for (var l = navLevel + 1; l <= 6; l++) {
+              delete $contexts[l];
+              delete $prevNavByLevel[l];
+            }
+          }
         });
       },