v1.0.0

Initial commit: styled-map-package Python reader and writer

Pure-Python (standard library only) reader and writer for the Styled Map
Package (.smp) archive format, ported from the JavaScript reference
implementation at https://github.com/digidem/styled-map-package.

Includes the Reader, Writer, a low-level write_smp_archive API, opt-in tile
deduplication with a matching reader path, and a test suite with cross-language
interop checks against the JavaScript reference. No third-party runtime
dependencies, so it can be vendored into the QGIS plugin
(https://github.com/digidem/qgis-smp-plugin).