- Add rotated 'Size' (left) and 'Snapshots' (right) axis titles in
the chart's outer margins so the two y-axes are self-describing.
- Bump the chart viewBox from 600x220 to 640x220 and lift padL from
56 to 72 so the rotated labels and byte tick numbers don't crowd.
- Dedupe the X-axis labels for short windows (1 or 2 days collapsed
the start/mid/end indices onto each other, stacking 'May 7' three
times); the 1-day case now centres a single label, 2-day uses
start+end only.
- Pin a lone data dot to the chart centre instead of the left edge
when len(days)==1, so it sits under the centred date label.
Goldens regenerated.
steve