telegram: rich messages render $…$ as math and collapse single newlines #1109

Since 4.41, postMessage({ markdown }) goes through sendRichMessage with the markdown passed unchanged (resolveRichMessage). Telegram's rich-message parser differs from the CommonMark the adapter assumes elsewhere:

• $…$ is inline math. MU ~$950 (-3.3% from $983.23). TSLA ~$403 renders 950(−3.3from983.23)… as a formula, and % inside it starts a TeX comment that drops the rest of the span.
• A single \n is a soft break, so line-per-item text (• a\n• b) becomes one paragraph. The MarkdownV2 path kept those lines.

\$ and trailing-backslash hard breaks both render correctly in sendRichMessage. Verified with the Bot API directly. Still present in 4.43.0.

Suggested fix: escape $ outside code, and either emit hard breaks for soft line breaks or document that callers must.