Rich messages are not ready for primetime: current Telegram clients can
render Bot API 10.1 rich messages as blank/unsupported bubbles and make
them hard to copy as plain text, which is worse than the legacy
MarkdownV2 path for command snippets and mobile handoffs. Default the
rich_messages toggle to False so replies stay on the copyable legacy
path; users opt in per bot via platforms.telegram.extra.rich_messages:
true. Updates adapter, gateway config default, example config, English +
zh-Hans docs, and the default/opt-in tests.
6183e8ce1b