feat: support Telegram rich message formatting options

[Rustam-Z]

Problem

Outbound formatting doesn't fully use Telegram's rich formatting capabilities.

Reference: https://core.telegram.org/bots/api#rich-message-formatting-options

Expected

• Properly support Telegram's rich formatting (entities / HTML / MarkdownV2 as appropriate).
• Ensure the markdown→Telegram conversion path covers the documented options.

From triage dump: link to Telegram rich-message-formatting-options

Labels: enhancement