replace hand-rolled string scanning with golang.org/x/net/html ParseFragment, fixing three infinite-loop paths that triggered on malformed/unclosed <pre> tags and an off-by-one in line counting (chroma always emits a trailing newline, so the old +1 overcounted every code block by one line) also remove the unused "markdown" template func — all prose rendering goes through markdownSegments, readme, or description Signed-off-by: eti <eti@eti.tf>