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

config/django/test.py

@@ -1,65 +0,0 @@
-"""
-Test settings for thrillwiki project.
-"""
-
-from .base import *
-
-# Test-specific settings
-DEBUG = False
-
-# Use in-memory database for faster tests
-DATABASES = {
-    "default": {
-        "ENGINE": "django.contrib.gis.db.backends.spatialite",
-        "NAME": ":memory:",
-    }
-}
-
-# Use in-memory cache for tests
-CACHES = {
-    "default": {
-        "BACKEND": "django.core.cache.backends.locmem.LocMemCache",
-        "LOCATION": "test-cache",
-    }
-}
-
-# Disable migrations for faster tests
-
-
-class DisableMigrations:
-    def __contains__(self, item):
-        return True
-
-    def __getitem__(self, item):
-        return None
-
-
-MIGRATION_MODULES = DisableMigrations()
-
-# Email backend for tests
-EMAIL_BACKEND = "django.core.mail.backends.locmem.EmailBackend"
-
-# Password hashers for faster tests
-PASSWORD_HASHERS = [
-    "django.contrib.auth.hashers.MD5PasswordHasher",
-]
-
-# Disable logging during tests
-LOGGING_CONFIG = None
-
-# Media files for tests
-MEDIA_ROOT = BASE_DIR / "test_media"
-
-# Static files for tests
-STATIC_ROOT = BASE_DIR / "test_static"
-
-# Disable Turnstile for tests
-TURNSTILE_SITE_KEY = "test-key"
-TURNSTILE_SECRET_KEY = "test-secret"
-
-# Test-specific middleware (remove caching middleware)
-MIDDLEWARE = [m for m in MIDDLEWARE if "cache" not in m.lower()]
-
-# Celery settings for tests (if Celery is used)
-CELERY_TASK_ALWAYS_EAGER = True
-CELERY_TASK_EAGER_PROPAGATES = True