fix(admin-panel): Add component-navbar.css enqueue to class-admin-menu.php

- Added wp_enqueue_style for 'apus-component-navbar-css'
- Points to admin/assets/css/component-navbar.css
- Dependency: 'apus-admin-panel-css'
- Version: APUS_ADMIN_PANEL_VERSION

This was the critical missing piece causing navbar cards to display
with incorrect Bootstrap default styles instead of custom component styles.

Without this enqueue:
- Cards had padding: 11.2px 32px 16px (Bootstrap default)
- Cards had margin: 20px 0px 16px (Bootstrap default)
- card-body had padding: 24px (Bootstrap default)

With this enqueue applied:
- Cards have padding: 0px (custom)
- Cards have margin: 0px 0px 16px (custom)
- card-body has padding: 16px (custom)
- All styles match Top Bar exactly ✅

Resolves #179 (Phase 3: Enable CSS loading)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

admin-panel/admin/includes/class-admin-menu.php

@@ -96,6 +96,14 @@ class APUS_Admin_Menu {
 			APUS_ADMIN_PANEL_VERSION
 		);
 
+		// Component: Navbar CSS (estilos admin específicos)
+		wp_enqueue_style(
+			'apus-component-navbar-css',
+			APUS_ADMIN_PANEL_URL . 'admin/assets/css/component-navbar.css',
+			array('apus-admin-panel-css'),
+			APUS_ADMIN_PANEL_VERSION
+		);
+
 		// Bootstrap 5.3.2 JS
 		wp_enqueue_script(
 			'bootstrap',