Link Ground Zero weather lookup coordinates

Docs/Terrain/TileRegistrySchema.md

@@ -78,6 +78,10 @@ Optional growing-zone fields follow the same rule. Crop viability, frost-free
 windows, and growing-season length are generated only for tiles with real source
 work or published packages and explicit growing-zone data.
 
+Optional weather lookup fields are stored only for active/source-backed tiles.
+For MVP, Ground Zero uses its tile-center latitude/longitude as the canonical
+real-world lookup coordinate for live weather and temperature.
+
 ### `terrain_tile_neighbors`
 
 Tracks adjacency for stitching and prefetching.
@@ -136,6 +140,26 @@ Required fields:
 - `data_basis`
 - `generated_at`
 
+### `terrain_tile_weather_lookup_metadata`
+
+Tracks the real-world coordinate and provider routing used to fetch live
+weather and temperature snapshots for a source-backed tile.
+
+Required fields:
+
+- `tile_id`
+- `lookup_latitude`
+- `lookup_longitude`
+- `coordinate_source`
+- `primary_provider`
+- `fallback_provider_eligible`
+- `lookup_rule`
+
+Optional fields:
+
+- `fallback_provider`
+- `generated_at`
+
 ### `terrain_tile_packages`
 
 Tracks generated downloadable packages.