Reload the browser on template and static changes in dev

Adds django-browser-reload: runserver already restarts on Python changes, but
the browser had to be refreshed by hand for every template or CSS edit. It also
watches static/, so a Tailwind rebuild now refreshes the page on its own.

Mounted only under DEBUG -- it injects a script into every HTML response and
serves an open event stream, neither of which belongs in production; a test
holds that line. Its endpoint is exempt from RequireMFAMiddleware, otherwise a
not-yet-enrolled staff user has the stream redirected away and live reload dies
on the MFA enrolment page, which is exactly a page we are restyling.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

rosterchief/settings.py

@@ -81,6 +81,13 @@ MIDDLEWARE = [
     "django.middleware.clickjacking.XFrameOptionsMiddleware",
 ]
 
+# Reload the browser when templates, static files or Python change. Dev only: it
+# injects a script tag into every HTML response and serves an open event stream,
+# neither of which belongs in production.
+if DEBUG:
+    INSTALLED_APPS += ["django_browser_reload"]
+    MIDDLEWARE += ["django_browser_reload.middleware.BrowserReloadMiddleware"]
+
 AUTHENTICATION_BACKENDS = [
     "django.contrib.auth.backends.ModelBackend",
     "allauth.account.auth_backends.AuthenticationBackend",