There's an edge case where the current phase of the budget was disabled.
In this case, the application was crashing.
I'm not sure what we should do regarding this case. Is it OK to allow
disabling the current phase? Is it OK to allow selecting a disabled
phase as the current phase?
Since I'm not sure about it, for now I'm leaving it the same way it was.
Co-authored-by: Julian Herrero <microweb10@gmail.com>
Before commit 28caabecd, it was clear which budgets were in draft mode
because their phase was "drafting".
Now the phase isn't "drafting" anymore, so we have to make it clear
somehow that the budget is a draft.
I'm using styles similar to the ones we added in commit 2f636eaf7 for
completed budgets but at the same time making them slightly different so
it's easy to differenciate completed and drafting budgets.
We're going to change it a bit, and using a component allows us to use
the `header` method and easily add a title to this page, which lacked
the `<title>` tag.
