Move cache+DB+download logic for /tiles/{z}/{x}/{y} and
/api/satellite/tiles/latlon out of Program.cs into TileService.
Endpoints now inject only ITileService + ILogger. Service owns
IMemoryCache (1h absolute / 30min sliding preserved). Added
TileBytes DTO; ITileService gains GetOrDownloadTileAsync and
DownloadAndStoreSingleTileAsync. 5 new unit tests cover cache
hit, repo hit, downloader fallback, and AZ-311 happy + error.
Build clean (0/0), unit suite 40/40. Resolves architecture
baseline F3 in code (docs handled by AZ-315).
Co-authored-by: Cursor <cursoragent@cursor.com>
Oleksandr Bezdieniezhnykh