feat: farm boundary pipeline — Phase 1, 2, 3 (AET/PET/MAI water stress)

[akshat163]

Summary

Adds the farm boundary pipeline to the CoRE Stack backend.

What's included

• Phase 1 (fetch_raw.py): Fetches S2-cell landscape data from the AnthroKrishi API for a given tehsil
• Phase 2 (convert.py): Converts raw JSON to GeoParquets — one per structure type (farm fields, trees, dug wells, farm ponds, other water bodies)
• Phase 3 (et_intersection.py): Downloads AET and PET rasters from GEE, computes per-farm MAI (Moisture Adequacy Index = AET/PET) and kharif water stress indicators per the India Drought Manual 2016
• Orchestrator (farm_boundary.py): Celery task chaining all three phases
• API endpoint: POST /api/v1/generate_farm_boundaries/

Files changed

• computing/farm_boundaries/ — new folder with all pipeline code
• computing/api.py — added generate_farm_boundaries endpoint
• computing/urls.py — registered the new URL
• utilities/constants.py — added FARM_BOUNDARIES_PATH and restored LIVESTOCKS