Text uploads are served without a charset in the Content-Type, causing mojiba...

Text uploads are served without a charset in the Content-Type, causing mojibake in browsers. Steps: POST /api/upload with {"tier":"10mb","contentType":"text/markdown"}, PUT a UTF-8 markdown file with Content-Type: text/markdown, then GET the publicUrl — em dashes and curly quotes render as "—" etc. because the file is served as bare text/markdown and browsers fall back to Windows-1252. Workaround: re-PUT with Content-Type: text/markdown; charset=utf-8, which is preserved and fixes rendering. Suggestion: default text/* uploads to charset=utf-8 when no charset is provided (or document that clients should always pass an explicit charset).