feat(messages): reply quotes show a media thumbnail (#151)

A reply to an image, video or sticker used to quote just the filename.
The quote (timeline) and the composer's reply-draft preview now carry a
36 px thumbnail from the event's own thumbnail, decrypted for E2EE media
via the same hook the gallery uses — never the full-size file. Clicking
still jumps to the original.

useDecryptedMediaUrl and getThumbMxc moved out of MediaGallery into
hooks/ and utils/ so components/message can use them without a cycle.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/components/message/Reply.tsx

@@ -8,6 +8,7 @@ import { getMxIdLocalPart } from '../../utils/matrix';
 import { LinePlaceholder } from './placeholder';
 import { randomNumberBetween } from '../../utils/common';
 import * as css from './Reply.css';
+import { ReplyMediaThumb, hasReplyMedia } from './ReplyMediaThumb';
 import { MessageBadEncryptedContent, MessageDeletedContent, MessageFailedContent } from './content';
 import { scaleSystemEmoji } from '../../plugins/react-custom-html-parser';
 import { useRoomEvent } from '../../hooks/useRoomEvent';
@@ -143,9 +144,12 @@ export const Reply = as<'div', ReplyProps>(
               <i>Original message not available</i>
             </Text>
           ) : (
-            <Text size="T300" truncate>
-              {badEncryption ? <MessageBadEncryptedContent /> : bodyJSX}
-            </Text>
+            <Box alignItems="Center" gap="200" style={{ minWidth: 0 }}>
+              {hasReplyMedia(replyEvent) && <ReplyMediaThumb mEvent={replyEvent} />}
+              <Text size="T300" truncate>
+                {badEncryption ? <MessageBadEncryptedContent /> : bodyJSX}
+              </Text>
+            </Box>
           )}
         </ReplyLayout>
       </Box>