Add time tracking to Cards

User Story

As a user of the deck app I would like to be able to see how much time I have spend on a task represented by a card. After completing a project I want to see how much time I spent in total and on each sub task. I want to see whether I maintained an allotted time budget and to be able to report it.

Implementation Proposal

Record Button

I think this could be implemented with a button on each card. The button could follow the common "record" symbol and when clicked would start a counter for this card. On start the button changes to a "stop" symbol (square). Alternatively the buttons can simply be called "Start Tracking Time" and "Stop Tracking Time".

Time display

Each card has a rectangular area displaying a time in hh:mm:ss format. It is greyed out when no time has been record. The time starts counting when a user presses the record button and stops when the user stops counting. It continues running when a user starts the button again.

Statistics

There is a cumulative display for each project that displays the sum of all cards.

Optional Features

• to correct time in case it was not stopped by mistake
  • allow manual editing of time by clicking on it OR
  • show "details" button where user can see a list of all recorded snippets and edit them, e.g. deleting the last recordin

No files, tests, or entry points are named. Review the card and project requirements in this issue first; done means users can start and stop timing cards, resume timing, see per-card and cumulative project totals, and verify time budgets.