Add to-do file

This allows me to track improvements we'd like to make, but not necessarily
straight away.

TODO.md

@@ -0,0 +1,17 @@
+# To-do
+
+* switch `ParameterValidator` to use `SECRET_KEY` if possible to minimize
+  non-standard settings
+* replace `internalNavigate` with inline flexbox layout
+* migrate to Django 4.2
+* add deployment script that runs migrations and collects static files
+* add tests for main pages returning 200
+* switch to `path` in URLconfs
+* review `apache2` directory - may be unused
+* standardise settings to replace `settings.py` and `djangocommonsettings.py`
+  with `settings/prod.py` and move `SECRET_KEY` to an environment variable
+
+
+# Done
+
+* install staticfiles app