- Use reply_parameters per the sendRichMessage spec instead of the
undocumented reply_to_message_id scalar (silently ignored -> reply
anchor quietly dropped).
- Latch rich sends off after an endpoint-capability failure (old PTB /
server without sendRichMessage) so every later reply doesn't pay a
doomed extra roundtrip; per-message BadRequests do NOT latch.
- Default rich_messages to OFF (opt-in) while the day-old Bot API 10.1
endpoint is validated live; revert the prompt-hint table guidance
until the default flips on.
- Tests: reply_parameters shape, send-latch behavior, BadRequest
non-latch; rich tests opt in explicitly via extra.