feat: major project restructure - move Django to backend dir and fix critical imports

- Restructure project: moved Django backend to backend/ directory
- Add frontend/ directory for future Next.js application
- Add shared/ directory for common resources
- Fix critical Django import errors:
  - Add missing sys.path modification for apps directory
  - Fix undefined CATEGORY_CHOICES imports in rides module
  - Fix media migration undefined references
  - Remove unused imports and f-strings without placeholders
- Install missing django-environ dependency
- Django server now runs without ModuleNotFoundError
- Update .gitignore and README for new structure
- Add pnpm workspace configuration for monorepo setup

templates/location/partials/search_results.html

@@ -1,17 +0,0 @@
-<div class="search-results-container">
-    {% if results %}
-        {% for result in results %}
-            <div class="p-2 cursor-pointer hover:bg-gray-100"
-                 data-action="click->location-map#selectLocation"
-                 data-result="{{ result|json }}">
-                <div class="font-medium">{{ result.name }}</div>
-                <div class="text-sm text-gray-500">
-                    {% if result.address.city %}{{ result.address.city }}, {% endif %}
-                    {{ result.address.country }}
-                </div>
-            </div>
-        {% endfor %}
-    {% else %}
-        <div class="p-2 text-gray-500">No results found</div>
-    {% endif %}
-</div>