Airspace overlay + route crossing alerts (CTR/TMA/restricted/danger)

[msupino]

Summary

Overlay Israeli airspace (CTR, TMA, restricted, danger, prohibited) with vertical limits and activation info, and warn when a route leg clips one.

Motivation

Avoiding or coordinating controlled and restricted airspace is core to VFR planning. NavAid already shows charts but has no machine-readable airspace or crossing detection.

Proposed UI

• Show airspace toggle in View; polygons drawn with class/vertical-limit labels.
• A route check: legs intersecting an airspace get flagged in the Flight Plan and/or on the map, with the airspace name + vertical limits.

Data

• New docs/data/airspace.json — polygons with class, name, lowerFt, upperFt, activation (and source/AIP attribution). Document in a wiki dataset page.

Implementation

• docs/app/draw.js — polygon rendering; docs/app/interact.js/io.js — leg-vs-polygon intersection + warnings; docs/app/core.js — strings (en + he).
• New dataset loader (lazy fetch like nav-waypoints/airfields).

Acceptance criteria

• Airspace polygons render with vertical limits when toggled.
• Route legs that cross are flagged with name + limits.
• Dataset documented + versioned (?v=N).
• en + he strings.

Note: sourcing accurate airspace geometry from the CAAI AIP is the main effort; scope can start with CTR/TMA only.