Update notice for Obeya run from a git clone

If you run Obeya from a clone of the repository, it now checks the clone's upstream when it starts and then once an hour. When new commits that change code are waiting, the bar shows how many there are and offers a "git pull" button, just like the installed app's update notice. Hover over the notice to see the commits. Click the button and Obeya pulls them and restarts on the new code, waiting until running agents and any recording are finished. If local commits or uncommitted edits make a clean pull impossible, there's no button, and the hover explains why and what to do.