Feat: datetime on items

[nelsonic]

As noted by @panoramix360 in #140 (comment) 💬
at present the default view of all items has very little insight/info on it:

This has been a deliberate choice to keep the interface decluttered.
However there is a lot of info/insight that could surface for people just by showing the date.

Todo

• Determine which dates are relevant to display. e.g: created_at, last_updated, last_timer_stop
  Pseudo logic: if the item has never been worked on then display the created_at with <label>: "Created:"
  if the item.text or tags were updated then show the updated_at date with the <label>: "Last updated:"
  finally if the item has a timer associated show the last timer.stop date+time with <label>: "Last worked on:"
• Decide where in the layout it makes sense to display date + time info.