0.7.0: focus on a habit

Focus on a habit.

• Start a timer on any habit from Today or Home: Free (counts up until you stop) or Pomodoro (rounds of focus and break, with Classic, Deep and Short presets and your own numbers, remembered for each habit).
• A slim bar on every page while a session runs, with the time in the tab title while the tab is in the background.
• A chime when a round or a break ends, and a rising one when the session finishes, in a sound you choose (or silent), plus a browser notification if you allow it.
• When you stop, say "I did it" to tick the habit for that day.
• A new Focus time card on Progress: the minutes you focused, in total and for each habit.
• The loading screens now fit small phones.