fix: Implement unified authentication system

- Created single auth-unified.ts module as the source of truth
- Deprecated old auth.ts and simple-auth.ts (now proxy to unified)
- Fixed dashboard SSR auth using Astro.cookies for better compatibility
- Added comprehensive auth test page at /auth-test-unified
- Resolved cookie handling issues in Docker environment

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

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

src/pages/dashboard.astro

@@ -6,12 +6,11 @@ import { verifyAuth } from '../lib/auth';
 // Enable server-side rendering for auth checks
 export const prerender = false;
 
-// Disable server-side auth check temporarily to fix redirect loop
-// We'll handle auth check on the client side in the script section
-// const auth = await verifyAuth(Astro.request);
-// if (!auth) {
-//   return Astro.redirect('/login');
-// }
+// Server-side auth check using cookies for better SSR compatibility
+const auth = await verifyAuth(Astro.cookies);
+if (!auth) {
+  return Astro.redirect('/login');
+}
 ---
 
 <Layout title="Dashboard - Black Canyon Tickets">