Fix race condition: save CSV to field-specific directory instead of global file

Fix on-demand vegetation index computation (NDVI, NDRE, EVI, PRI) - compute from bands when no cache exists

Add computed indices support (NDVI, EVI, NDRE, PRI)

v2.1.0 Production-ready with CSV downloads and detailed logging

Fix: Add on-demand prediction for /timeseries when no cache

Fix: temp file cleanup after predictions

v2.0.0 Persistent prediction with caching and index computation

v1.0.0 TimeSeries Service with AutoNHITS