Complete early roadmap foundation and calendar helpers

Docs/Terrain/TileRegistrySchema.md

@@ -69,6 +69,15 @@ Required fields:
 - `created_at`
 - `updated_at`
 
+Optional solar/time fields should be stored only for tiles that have real source
+work or a published package, not for every theoretical 1 km square. The
+Earth-scale registry may eventually contain hundreds of millions of possible
+tiles, so solar metadata is generated on demand for existing/active tiles.
+
+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.
+
 ### `terrain_tile_neighbors`
 
 Tracks adjacency for stitching and prefetching.
@@ -93,6 +102,40 @@ Required fields:
 - `source_version`
 - `coverage_status`
 
+### `terrain_tile_solar_metadata`
+
+Tracks local time-zone and solar lookup metadata for tiles that actually exist
+in the registry as source-backed, generated, validated, packaged, or published
+tiles.
+
+Required fields:
+
+- `tile_id`
+- `time_zone_id`
+- `standard_utc_offset_hours`
+- `daylight_utc_offset_hours`
+- `solar_model`
+- `generated_at`
+
+### `terrain_tile_growing_season_metadata`
+
+Tracks the active growing zone and season window for source-backed tiles. Crop
+systems use this table to decide whether a crop with a given maturity time can
+finish before the represented region's growing season closes.
+
+Required fields:
+
+- `tile_id`
+- `growing_zone_label`
+- `climate_profile`
+- `growing_season_start_day`
+- `growing_season_end_day`
+- `frost_free_days`
+- `min_average_growing_temp_c`
+- `crop_safety_buffer_days`
+- `data_basis`
+- `generated_at`
+
 ### `terrain_tile_packages`
 
 Tracks generated downloadable packages.