Remove timex, earmark, dns_cluster deps; add local implementations
- Replace Timex with regex-based timestamp parser (broader format support)
- Replace Earmark with local Markdown.to_html! (headings, code blocks,
tables, lists, inline formatting, links, horizontal rules)
- Remove dns_cluster (unused, single-instance deployment)
- Add stream_data property tests for timestamp parsing (5 properties
covering ISO, US dates, AM/PM, format roundtrips, garbage rejection)
- Removes transitive deps: combine, tzdata, hackney, certifi, metrics,
mimerl, parse_trans, ssl_verify_fun
Graham McIntire
93f2c32971