fix: migrate STATICFILES_STORAGE to STORAGES for Django 5.2 compat

Django 5.1+ removes STATICFILES_STORAGE in favour of the STORAGES dict.
The old setting was silently ignored on Django 5.2, causing StaticFilesStorage
(the default) to be used instead of CompressedManifestStaticFilesStorage.

Result: no content-hashed filenames, no staticfiles.json manifest, and
Cloudflare caching /static/css/styles.css indefinitely with no cache
busting on deploy.

Fix: use STORAGES in base.py (CompressedManifestStaticFilesStorage) and
development.py (plain StaticFilesStorage, whitenoise disabled in dev).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

config/settings/development.py

@@ -9,7 +9,15 @@ INTERNAL_IPS = ["127.0.0.1"]
 # media files natively when DEBUG=True (via django.contrib.staticfiles + the
 # media URL pattern in urls.py).
 MIDDLEWARE = [m for m in MIDDLEWARE if m != "whitenoise.middleware.WhiteNoiseMiddleware"]
-STATICFILES_STORAGE = "django.contrib.staticfiles.storage.StaticFilesStorage"
+STORAGES = {
+    "default": {
+        "BACKEND": "django.core.files.storage.FileSystemStorage",
+    },
+    "staticfiles": {
+        "BACKEND": "django.contrib.staticfiles.storage.StaticFilesStorage",
+    },
+}
+
 
 try:
     import debug_toolbar  # noqa: F401