tabulaflow route sprite assets
==============================

Files:
- tf-route-sprite.json
- tf-route-sprite.png
- tf-route-sprite@2x.json
- tf-route-sprite@2x.png

These interstate shield backgrounds and the airport icon are generated for
tabulaflow and bundled locally for MapLibre labels. They are custom assets,
not copied from Google Maps or another map provider.

Design:
- Runtime display sizes are 26x30 CSS px for 1- and 2-digit shields, and
  32x30 CSS px for 3-digit shields, preserving the draft SVG proportions.
- The airport icon display size is 20x20 CSS px.
- The @2x sprite is generated at double pixel dimensions with pixelRatio 2.
- Shield colors are tuned for the light map theme: red #f25f6b, blue #5f72d6.
- Regenerate with: uv run scripts/app/generate_route_sprite.py
