Each profile sample now carries the tallest building height within 80m
of the path point. The candidate-detail SVG renders these as a red
polygon stacked on top of the terrain so blockage from buildings is
visible alongside ridges. max_obstacle_m now reflects building tops too,
so the clearance label downgrades when buildings sit on the link.
- Detail panel now reads as an aiming card: "Aim 220° (SW) · clearance +12 ft"
with the precise bearing in degrees, plus rover/obstacle elev on a second line
- Elevation profile labels swapped from min/max-of-profile to start (rover) and
end (station) elevations, since their positions in the chart now match
- Map draws a dashed indigo polyline from the candidate to each selected
station when a candidate is opened; cleared when the panel closes