[feature] projects should have a concept of archiving

[masukomi]

you should be able to "archive" a project such that it no longer shows up in the list of hey projects

why

because if we're going to build autocomplete tools and GUIs they shouldn't be asking you to choose from projects you no longer care about.

Edge case

if you start a new timer with a project name that's been previously archived it should unarchive that project. Maybe the client came back. Doesn't matter why you've started using it, just that if you are, it's no longer conceptually in the "archive".

Side note

we'll eventually have to do this with tags too...