Function getSectionBBox

getSectionBBox(route: Route, section: SectionProps): OptionalBBox
Calculates the bounding box for a route section.

This function computes a bbox by sampling coordinates from the section at three key points:
- Start point (startPointIndex)
- Middle point (midpoint between start and end)
- End point (endPointIndex)
Parameters
- route: Route
  The route containing the section
- section: SectionProps
  The section to calculate the bbox for
Returns OptionalBBox
The bounding box as [minLng, minLat, maxLng, maxLat], or undefined if the section or route is invalid
Remarks
- Samples three points for efficiency while maintaining good accuracy
- Returns undefined if the route has no coordinates or section indices are invalid
- Uses existing bbox utilities for consistent calculation
Example
```
const section = route.properties.sections.countries[0];
// section = { id: 'section-1', startPointIndex: 0, endPointIndex: 3, countryCodeISO3: 'NLD' }

const bbox = getSectionBBox(route, section);
// Returns: [minLng, minLat, maxLng, maxLat] spanning the section, or undefined
```