Docs/Changelog: add missing entry for #18586 (#18604)

Merged via /review-pr -> /prepare-pr -> /merge-pr.

Prepared head SHA: 513498364543fb1986950a9aabfffc8472a02a18
Co-authored-by: sebslight <19554889+sebslight@users.noreply.github.com>
Co-authored-by: sebslight <19554889+sebslight@users.noreply.github.com>
Reviewed-by: @sebslight

CHANGELOG.md

@@ -29,6 +29,7 @@ Docs: https://docs.openclaw.ai
 - Telegram: keep draft-stream preview replies attached to the user message for `replyToMode: "all"` in groups and DMs, preserving threaded reply context from preview through finalization. (#17880) Thanks @yinghaosang.
 - Telegram: disable block streaming when `channels.telegram.streamMode` is `off`, preventing newline/content-block replies from splitting into multiple messages. (#17679) Thanks @saivarunk.
 - Telegram: route non-abort slash commands on the normal chat/topic sequential lane while keeping true abort requests (`/stop`, `stop`) on the control lane, preventing command/reply race conditions from control-lane bypass. (#17899) Thanks @obviyus.
+- Telegram: keep DM-topic replies and draft previews in the originating private-chat topic by preserving positive `message_thread_id` values for DM threads. (#18586) Thanks @sebslight.
 - Telegram: prevent streaming final replies from being overwritten by later final/error payloads, and suppress fallback tool-error warnings when a recovered assistant answer already exists after tool calls. (#17883) Thanks @Marvae and @obviyus.
 - Memory/QMD: scope managed collection names per agent and precreate glob-backed collection directories before registration, preventing cross-agent collection clobbering and startup ENOENT failures in fresh workspaces. (#17194) Thanks @jonathanadams96.
 - Auto-reply/TTS: keep tool-result media delivery enabled in group chats and native command sessions (while still suppressing tool summary text) so `NO_REPLY` follow-ups do not drop successful TTS audio. (#17991) Thanks @zerone0x.