feat: Add comprehensive help documentation system and plugin creation page

- Add CreatePlugin.tsx page for custom plugin creation with code editor
- Add HelpButton component for contextual help links
- Create 21 new help pages covering all dashboard features:
  - Core: Dashboard, Scheduler, Tasks
  - Manage: Customers, Services, Resources, Staff
  - Communicate: Messages (Ticketing already existed)
  - Money: Payments
  - Extend: Plugins overview and creation guide
  - Settings: General, Resource Types, Booking, Appearance, Email, Domains, API, Auth, Billing, Quota
- Update HelpGuide.tsx as main documentation hub with quick start guide
- Add routes for all help pages in App.tsx
- Add HelpButton to Dashboard, Customers, Services, and Tasks pages

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

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

frontend/src/components/HelpButton.tsx

@@ -0,0 +1,33 @@
+/**
+ * HelpButton Component
+ *
+ * A contextual help button that appears at the top-right of pages
+ * and links to the relevant help documentation.
+ */
+
+import React from 'react';
+import { Link } from 'react-router-dom';
+import { HelpCircle } from 'lucide-react';
+import { useTranslation } from 'react-i18next';
+
+interface HelpButtonProps {
+  helpPath: string;
+  className?: string;
+}
+
+const HelpButton: React.FC<HelpButtonProps> = ({ helpPath, className = '' }) => {
+  const { t } = useTranslation();
+
+  return (
+    <Link
+      to={helpPath}
+      className={`inline-flex items-center gap-1.5 px-3 py-1.5 text-sm text-gray-500 dark:text-gray-400 hover:text-brand-600 dark:hover:text-brand-400 hover:bg-gray-100 dark:hover:bg-gray-800 rounded-lg transition-colors ${className}`}
+      title={t('common.help', 'Help')}
+    >
+      <HelpCircle size={18} />
+      <span className="hidden sm:inline">{t('common.help', 'Help')}</span>
+    </Link>
+  );
+};
+
+export default HelpButton;