The district-name watermark inside the arrests-over-time chart was
redundant with the page's own heading and was the direct cause of a label
collision (a high point's rate label rendered on top of it). Removes it.
Two more collisions, both edge cases the screenshot happened to hit: the
first wave's label sat close enough to the plot's top that it could
overlap the topmost gridline text, and a point sitting flush on the plot's
left edge had its center-anchored label bleed into the y-axis tick labels.
Fixes both with more vertical clearance and edge-aware text anchoring
(first point anchors right, last point anchors left, matching the same
fix already applied to chart 4's wave ticks before that chart was cut).
Adds a shared niceTicks() utility (Heckbert's nice-numbers algorithm) so
axis ticks read as round numbers (0/100/200) instead of arbitrary
fractions of the data max (0/113/226/339) — applied to all three charts
for consistency. Also fixes a legend/mark mismatch in the arrests-over-time
chart (the modeled series legend showed a diamond; the actual mark is a
dot) by adding a proper 'dot' shape to ChartLegend.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
