fix: resolve getNodeCollapsedState() method call in tree item template

Fixes incorrect context reference in tree item blade template where
$this->getNodeCollapsedState($record) was called from a blade component
context where $this doesn't refer to the Livewire component.

Changed to use $tree->getLivewire()->getNodeCollapsedState($record) to
properly access the method from the correct Livewire component context.

This enables proper node collapse state functionality for tree items,
allowing developers to override getNodeCollapsedState() to control
initial tree node visibility (e.g., starting with collapsed nodes).

Fixes #88

Author: cklei-carly

resources/css/plugin.css

@@ -9,4 +9,8 @@
 @import './button.css';
 @import './custom-nestable-item.css';
 
-@source '../views/**/*.blade.php';
+@source "../views";
+
+.filament-tree-list.hidden {
+    display: none;
+}