Switch to streaming decompression

Right now full replay is decompressed, and then parsed.

It's quite wasteful both from memory usage perspective, but also when somebody just wants to read header and that's it.

This issue is to switch replay parsing to streaming decompression.

Start by locating the replay parsing entry point and the current path that fully decompresses an .sdfz demo before parsing. Update the flow so decompression is consumed incrementally, including when only the header is requested, and verify that full replay parsing still works without loading the entire decompressed replay into memory.

Written by the indexing model from the issue text.