This will stop us repeatedly forgetting to add `novalidate` and
`autocomplete='off'` to our forms (which is how most of them are set
up).
It uses sensible defaults, based on how we most-commonly configure
forms:
- most of our forms are `post`ed (but this can be overridden)
- `autocomplete` should only be enabled where it makes sense, otherwise
it’s more annoying than useful (but this can be overriden)
- we should never be using HTML5 form validation because our own error
styles and messages are better
There are way too many links in the top nav now (when you’re using the
site as a platform admin).
And how often are you going to look at the letter jobs page really?
This commit adds some internal navigation for the platform admin area of
the platform, copying the style that works for navigating a single
service.
