feat: Districts table and geojson stub

migrations/00006_create_districts_table.sql

@@ -0,0 +1,17 @@
+-- +goose Up
+-- Administrative districts, keyed by KATO code. Geometry is the district
+-- boundary stored as MultiPolygon in EPSG:4326. Populated from a districts
+-- GeoJSON file via the `gis import-districts` subcommand.
+CREATE TABLE districts (
+    id          UUID PRIMARY KEY  DEFAULT gen_random_uuid(),
+    kato        TEXT NOT NULL,
+    name        TEXT NOT NULL,
+    coordinates geometry(MultiPolygon, 4326) NOT NULL,
+    created_at  TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+CREATE UNIQUE INDEX uq_districts_kato ON districts (kato);
+CREATE INDEX idx_districts_coordinates ON districts USING GIST (coordinates);
+
+-- +goose Down
+DROP TABLE districts;