refactor: standardize admin templates with shared macros

Migrate all admin templates to use standardized components:
- Use tabs macros (tabs_nav, tab_button) for tab navigation
- Use number_stepper for quantity/numeric inputs
- Use headers macros for consistent page layouts
- Use modals macros for dialog components

Affected pages: dashboard, settings, logs, content-pages, companies,
vendors, users, imports, marketplace, code-quality, and more.

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/templates/admin/user-create.html

@@ -1,27 +1,13 @@
 {# app/templates/admin/user-create.html #}
 {% extends "admin/base.html" %}
+{% from 'shared/macros/headers.html' import page_header %}
 
 {% block title %}Create User{% endblock %}
 
 {% block alpine_data %}adminUserCreate(){% endblock %}
 
 {% block content %}
-<!-- Page Header -->
-<div class="flex items-center justify-between my-6">
-    <div>
-        <h2 class="text-2xl font-semibold text-gray-700 dark:text-gray-200">
-            Create New User
-        </h2>
-        <p class="text-sm text-gray-600 dark:text-gray-400 mt-1">
-            Add a new user to the platform
-        </p>
-    </div>
-    <a href="/admin/users"
-       class="flex items-center px-4 py-2 text-sm font-medium leading-5 text-gray-700 transition-colors duration-150 bg-white border border-gray-300 rounded-lg dark:text-gray-400 dark:border-gray-600 dark:bg-gray-800 hover:border-gray-400 focus:outline-none">
-        <span x-html="$icon('arrow-left', 'w-4 h-4 mr-2')"></span>
-        Back to Users
-    </a>
-</div>
+{{ page_header('Create New User', subtitle='Add a new user to the platform', back_url='/admin/users', back_label='Back to Users') }}
 
 <!-- Create Form -->
 <form @submit.prevent="handleSubmit" class="px-4 py-3 mb-8 bg-white rounded-lg shadow-md dark:bg-gray-800">