Skewed isotherms, dry adiabats, and mixing-ratio lines were drifting
outside the frame at the corners — most visibly the warm-side
isotherms exiting the right edge near the top of the diagram. The
existing `clip_polyline/1` only filtered with a ±200 px slack, so
segments crossing the boundary still drew past the frame.
Wrap every grid layer + the T/Td/parcel polylines in a
`<g clip-path="url(#skewt-plot-clip)">`. The clipPath defines a
rectangle from (left, top) to (right, bottom). Frame outline and
axis labels stay outside the clip group so they keep rendering at
the box edge unchanged. The hover-cursor crosshair also lives
outside the clip so its readout box can sit flush against the plot
corner without being trimmed.
mix test: 2,902 / 2,902 + 221 properties green. mix credo --strict
clean.
Graham McIntire
b34b186e61