fix: update remaining replyToMode "first" defaults to "off"

- src/channels/dock.ts: core channel dock fallback
- src/auto-reply/reply/reply-routing.test.ts: test expectation
- docs/zh-CN/channels/telegram.md: Chinese docs reference

Comprehensive grep confirms no remaining Telegram-specific "first"
defaults after this commit.

src/channels/dock.ts

@@ -115,7 +115,7 @@ const DOCKS: Record<ChatChannelId, ChannelDock> = {
       resolveToolPolicy: resolveTelegramGroupToolPolicy,
     },
     threading: {
-      resolveReplyToMode: ({ cfg }) => cfg.channels?.telegram?.replyToMode ?? "first",
+      resolveReplyToMode: ({ cfg }) => cfg.channels?.telegram?.replyToMode ?? "off",
       buildToolContext: ({ context, hasRepliedRef }) => {
         const threadId = context.MessageThreadId ?? context.ReplyToId;
         return {