indicate that date columns are scrolled to the past

[ke352802081770314]

sometimes I scroll back in the timeline, e.g. to research some events or review what happened.
recently, I had scrolled back, and later (I didn't close the Loop app, just blanked the screen, and unlocked it later, or switched between apps) re-visited Loop Habit Tracker to enter some new data. I didn't notice that the dates were scrolled and overwrote old stuff by mistake. My eyesight isn't that good and the date numbers are really tiny and with weak contrast. (Luckily, I then thought, "hang on, I didn't do "that" today - other line's content - oh dear this isn't today" so I noticed and corrected my mistake)
Similar to a suggestion in #466 (May 31, 2020 with the ⇆ symbol) I would suggest that if the timeline is scrolled to the past, a symbol appears to the left of the dates, in the empty space above the habit titles, to alert me of the fact that the timeline is scrolled. or even a text "past data" but of course that would need to be localized. Maybe it would even be a button that gets me back to today 📅↺, no matter how far into the past I scrolled, so that I don't have to keep wiping until it doesn't move any more.

As mentioned it would also help if the date numbers were bigger, e.g. as big as the numeric habit values, just not bold.

[herrbrixter]

This can be solved by #2173 . If past entries are locked, then mistakes could be prevented.