Top-of-climb / top-of-descent + vertical profile

[msupino]

Summary

Model climb and descent instead of treating every leg as flat cruise: compute TOC/TOD points from climb/descent rates and show a simple vertical profile.

Motivation

Real time/fuel/altitude vary during climb and descent. Flat-cruise legs misstate ETE and fuel for routes with altitude changes.

Proposed UI

• Use per-profile climb/descent rate + speed (#aircraft-profiles).
• Mark TOC/TOD along the affected leg on the map; show a small altitude-vs-distance profile strip in the Flight Plan modal.
• Time/fuel for climb/descent segments use climb/descent performance.

Implementation

• docs/app/io.js — segment a leg at TOC/TOD; docs/app/draw.js — TOC/TOD markers + profile strip; docs/app/core.js — strings (en + he).

Acceptance criteria

• TOC/TOD computed from rates and shown.
• Climb/descent time + fuel differ from cruise.
• Vertical profile renders.
• en + he strings.