v0.1.0 of hyper_render_epub

EPUB container support for HyperRender. Unzips an .epub, parses its OPF manifest/spine/TOC, and resolves chapters to HyperViewer-ready content. Changelog excerpt: Initial release — **not publishable yet**: it depends on `hyper_render: ^1.7.0`, which is not on pub.dev. `EpubReader`needs `HyperViewer.imageLoader`(unreleased, on `main`) to decode the inline `data:`URIs chapters carry, so this package…