feat(tenant): Add public-facing landing page for business subdomains

- New TenantLandingPage component with 'Coming Soon' message
- Shows business name derived from subdomain
- Has 'Sign In' button that goes to /login
- 'Powered by SmoothSchedule' footer
- Will be customizable later for each tenant

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

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

frontend/src/pages/TenantLandingPage.tsx

@@ -0,0 +1,96 @@
+import React from 'react';
+import { Link } from 'react-router-dom';
+import { Calendar, Clock, ArrowRight, Building2 } from 'lucide-react';
+
+interface TenantLandingPageProps {
+  subdomain: string;
+}
+
+const TenantLandingPage: React.FC<TenantLandingPageProps> = ({ subdomain }) => {
+  // Format subdomain for display (capitalize first letter, replace hyphens with spaces)
+  const displayName = subdomain
+    .split('-')
+    .map(word => word.charAt(0).toUpperCase() + word.slice(1))
+    .join(' ');
+
+  return (
+    <div className="min-h-screen bg-gradient-to-br from-indigo-50 via-white to-purple-50 dark:from-gray-900 dark:via-gray-800 dark:to-indigo-900">
+      {/* Header */}
+      <header className="absolute top-0 left-0 right-0 z-10">
+        <div className="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8 py-6">
+          <div className="flex items-center justify-between">
+            <div className="flex items-center gap-3">
+              <div className="w-10 h-10 bg-indigo-600 rounded-lg flex items-center justify-center">
+                <Building2 className="w-6 h-6 text-white" />
+              </div>
+              <span className="text-xl font-bold text-gray-900 dark:text-white">
+                {displayName}
+              </span>
+            </div>
+            <Link
+              to="/login"
+              className="inline-flex items-center gap-2 px-5 py-2.5 bg-indigo-600 text-white rounded-lg hover:bg-indigo-700 transition-colors font-medium"
+            >
+              Sign In
+              <ArrowRight className="w-4 h-4" />
+            </Link>
+          </div>
+        </div>
+      </header>
+
+      {/* Main Content */}
+      <main className="flex items-center justify-center min-h-screen px-4">
+        <div className="text-center max-w-2xl mx-auto">
+          {/* Icon */}
+          <div className="mb-8">
+            <div className="inline-flex items-center justify-center w-24 h-24 bg-indigo-100 dark:bg-indigo-900/30 rounded-full">
+              <Calendar className="w-12 h-12 text-indigo-600 dark:text-indigo-400" />
+            </div>
+          </div>
+
+          {/* Title */}
+          <h1 className="text-4xl sm:text-5xl font-bold text-gray-900 dark:text-white mb-4">
+            {displayName}
+          </h1>
+
+          {/* Coming Soon Badge */}
+          <div className="inline-flex items-center gap-2 px-4 py-2 bg-amber-100 dark:bg-amber-900/30 text-amber-700 dark:text-amber-400 rounded-full mb-6">
+            <Clock className="w-4 h-4" />
+            <span className="text-sm font-medium">Coming Soon</span>
+          </div>
+
+          {/* Description */}
+          <p className="text-lg text-gray-600 dark:text-gray-400 mb-8 max-w-md mx-auto">
+            We're setting up our online booking system. Check back soon to schedule your appointment!
+          </p>
+
+          {/* CTA Buttons */}
+          <div className="flex flex-col sm:flex-row items-center justify-center gap-4">
+            <Link
+              to="/login"
+              className="inline-flex items-center gap-2 px-6 py-3 bg-indigo-600 text-white rounded-lg hover:bg-indigo-700 transition-colors font-medium shadow-lg shadow-indigo-500/25"
+            >
+              Staff Login
+              <ArrowRight className="w-4 h-4" />
+            </Link>
+          </div>
+
+          {/* Powered by */}
+          <p className="mt-12 text-sm text-gray-500 dark:text-gray-500">
+            Powered by{' '}
+            <a
+              href="https://smoothschedule.com"
+              target="_blank"
+              rel="noopener noreferrer"
+              className="text-indigo-600 dark:text-indigo-400 hover:underline"
+            >
+              SmoothSchedule
+            </a>
+          </p>
+        </div>
+      </main>
+    </div>
+  );
+};
+
+export default TenantLandingPage;