Replace the line-based --- heuristic with a scan over PureYAML's
resumable token scanner, so a --- inside a quoted scalar can no longer
misfire as a document boundary and directives stay attached to the
document they introduce. Add a differential suite that checks the new
scanner against the old line-based reference across generated streams
and the full Geekbench corpus.
Swap the PureYAML and SwiftWASIHTTPClient package URLs to Codeberg and
replace the shields.io GitHub badges with Forgejo Actions badges. The
WASM site link still needs rehosting, tracked in #2.
Closes#1
