Round-tripped the per-pixel argmax raster from the droplet so the HF
Space can vectorise it onto WGS84 polygons and the MapLibre layer
actually paints the live model output. Was: only terramind_synthesis's
local fallback path generated polygons; everything else returned
class fractions only and the map showed nothing.
Wire format: droplet's /v1/prithvi-pluvial and /v1/terramind responses
gain `pred_b64` (uint8 base64) + `pred_shape` + (terramind only)
`class_labels`. Small payload — 224x224 uint8 round-trips in ~50 KB.
HF side:
- new app/context/_polygonize.py: polygonize_class_raster() and
polygonize_binary_mask() helpers
- app/context/eo_chip_cache.py adds `bounds_4326` to chip output
- app/context/terramind_nyc lulc/buildings accept bounds_4326,
_try_remote polygonises the response and attaches polygons_geojson
- app/context/terramind_synthesis.py polygonises the remote response
- app/flood_layers/prithvi_live.py polygonises the remote water mask
- app/fsm.py threads chip.boun…
