Package-level declarations

Read-only snapshot of platform/device information, resolved once per platform target (expect/actual). Every field here is sent as an x-mosaic-* header (x-mosaic-platform-name, x-mosaic-device, etc.) on every outgoing HTTP request, via MosaicHeadersPlugin — so a backend can branch on client platform/device/locale/theme without the DSL author having to declare that data explicitly on each request. It's a plain object, not Koin-injected, so a custom EventRunner/TileRenderer can also read it directly for its own purposes.