Put a user message's copy button beside its timestamp

The copy button sat on its own row above the group's time, costing a
line of vertical space for nothing. It now shares that row, left of the
timestamp, the way a bot message's actions already do. A file-only
message leaves no gap: only messages with text get a button, picked by
copyableMessages.

src/pages/admin/bots/[bot_id]/(partials)/user-message.tsx

@@ -1,8 +1,6 @@
 import { memo } from "react";
-import Row from "@moduletrace/twui/layout/Row";
 import Stack from "@moduletrace/twui/layout/Stack";
 import type { BotMessageWithAttachments } from "@/src/types";
-import CopyMessageButton from "./copy-message-button";
 import MessageAttachments from "./message-attachments";
 import MessageReactions from "./message-reactions";
 import MessageReplyQuote from "./message-reply-quote";
@@ -17,7 +15,8 @@ type Props = {
  * One user message: the quoted message it answers, its files, then its
  * text (a file-only message has no bubble) and the bot's reactions to it.
  * The user doesn't reply to or react to their own messages, but they can
- * copy one. Memoized, like `BotMessageLine`.
+ * copy one: the group's copy buttons sit beside its timestamp, in
+ * `UserMessageGroup`. Memoized, like `BotMessageLine`.
  */
 function UserMessage({ message, bot_name }: Props) {
     return (
@@ -37,11 +36,6 @@ function UserMessage({ message, bot_name }: Props) {
                     reactions={message.reactions}
                 />
             ) : null}
-            {message.text ? (
-                <Row className="gap-3! items-center">
-                    <CopyMessageButton text={message.text} />
-                </Row>
-            ) : null}
         </Stack>
     );
 }