feat: complete monorepo structure with frontend and shared resources

- Add complete backend/ directory with full Django application
- Add frontend/ directory with Vite + TypeScript setup ready for Next.js
- Add comprehensive shared/ directory with:
  - Complete documentation and memory-bank archives
  - Media files and avatars (letters, park/ride images)
  - Deployment scripts and automation tools
  - Shared types and utilities
- Add architecture/ directory with migration guides
- Configure pnpm workspace for monorepo development
- Update .gitignore to exclude .django_tailwind_cli/ build artifacts
- Preserve all historical documentation in shared/docs/memory-bank/
- Set up proper structure for full-stack development with shared resources

backend/templates/404.html

@@ -0,0 +1,15 @@
+{% extends "base/base.html" %}
+
+{% block title %}Page Not Found{% endblock %}
+
+{% block content %}
+<div class="container px-4 py-16 mx-auto">
+    <div class="text-center">
+        <h1 class="mb-4 text-4xl font-bold">404 - Page Not Found</h1>
+        <p class="mb-8 text-lg">The page you're looking for doesn't exist or has been moved. Please try again in a while.</p>
+        <a href="/" class="inline-block px-4 py-2 font-bold text-white bg-blue-600 rounded hover:bg-blue-700">
+            Return Home
+        </a>
+    </div>
+</div>
+{% endblock %}