Demos go public when you approve the work

Obeya can now put a task's demo on a public demo site by itself as soon as you approve the task, so you no longer have to click Share separately. A new demo can replace the task's earlier page, or it can be added next to it when the new one only adds to the earlier demo. If the upload fails, the work still lands and you can share again later. When work goes straight onto main, the commit message links to the demo page, so anyone reading the history can watch the change. Obeya's own demos will be collected at demos.obeya.si, with links from the README and obeya.si, so newcomers can see every feature in action.