fix(auto-reply): land #31080 from @scoootscooob

Co-authored-by: scoootscooob <zhentongfan@gmail.com>

src/auto-reply/tokens.ts

@@ -17,6 +17,16 @@ export function isSilentReplyText(
   return new RegExp(`^\\s*${escaped}\\s*$`).test(text);
 }
 
+/**
+ * Strip a trailing silent reply token from mixed-content text.
+ * Returns the remaining text with the token removed (trimmed).
+ * If the result is empty, the entire message should be treated as silent.
+ */
+export function stripSilentToken(text: string, token: string = SILENT_REPLY_TOKEN): string {
+  const escaped = escapeRegExp(token);
+  return text.replace(new RegExp(`(?:^|\\s+)${escaped}\\s*$`), "").trim();
+}
+
 export function isSilentReplyPrefixText(
   text: string | undefined,
   token: string = SILENT_REPLY_TOKEN,