[AZ-373] Refactor C20: drop MapsVersion from new writes (option a)

- Stop writing "downloaded_YYYY-MM-DD" into tiles.maps_version: new rows
  bind @MapsVersion to NULL via TileService.BuildTileEntity.
- Retain the tiles.maps_version column (coderule.mdc forbids unprompted
  column drops); pre-existing rows keep their values for forensics.
- Remove MapsVersion property from DownloadTileResponse (API wire shape)
  and TileMetadata (internal DTO); OpenAPI schema regenerates from the
  DTO via Swashbuckle.
- Add 3 AC tests in TileServiceTests covering the captured-entity write
  (AC-1) and the DTO/wire-shape removal (AC-2).
- Update integration-test local DTO + console output; refresh docs in
  common_dtos.md, services_tile_service.md, data_model.md.
- Archive AZ-373 task file: todo/ -> done/.

174 unit + 5 smoke pass.

Co-authored-by: Cursor <cursoragent@cursor.com>

SatelliteProvider.Common/DTO/DownloadTileResponse.cs

@@ -9,7 +9,6 @@ public record DownloadTileResponse
     public double TileSizeMeters { get; set; }
     public int TileSizePixels { get; set; }
     public string ImageType { get; set; } = string.Empty;
-    public string? MapsVersion { get; set; }
     public int? Version { get; set; }
     public string FilePath { get; set; } = string.Empty;
     public DateTime CreatedAt { get; set; }