Match the reference enthalpy-axis layout

[iguchi-lab]

What changed

• numerically calculate the intersection between each 10–120 kJ/kg(DA) enthalpy line and the diagonal enthalpy axis
• extend every blue enthalpy line continuously to its axis intersection
• anchor the 0 kJ/kg(DA) line at the rounded lower-left axis endpoint
• show scale labels from 10 to 120, matching the supplied reference
• replace sampled axis-band segments with compact perpendicular tick marks
• place scale numbers consistently on one side of the axis
• move the enthalpy-axis title 24 px normal to the opposite side so it no longer overlaps the axis

Why

The previous version clipped enthalpy lines at the saturation boundary and placed the axis title too close to the diagonal line. This update follows the supplied reference chart.

Validation

The chart regression test verifies all 13 enthalpy lines reach the axis or its rounded endpoint, checks the 10–120 tick labels, and verifies the title offset and SVG paths.