fix(messages): render mobile-sent image/file/voice/video attachments

Live-confirmed in a real group ("seq测试", tenant 10001) that image
messages sent from Android and iOS render as completely blank bubbles
on web, and the chat list's own preview for one showed the literal
string "undefined". Root cause confirmed by querying the actual
im_messages/im_group_messages rows: mobile apps send image/file/voice/
video as a flat, non-Drafty content object (`{file_id,
thumbnail_file_id, mime, width, height, name, size, ref?, preref?}`)
tagged only by `head['x-im-type']`, not as a real Drafty `{txt,fmt,ent}`
document the way this web client's own sender (attachments.ts) always
builds. renderDrafty/formatMessagePreview had no case for this shape
and silently produced nothing / "undefined" -- the exact same failure
pattern already fixed once for `contact_card` (see dispatch.ts's
existing contactCardContentOf), just not yet extended to attachments.

Adds mobileAttachmentContentOf (dispatch.ts), normalizing `ref`/
`preref` from `file_id`/`thumbnail_file_id` when the wire message
omits them (confirmed both cases occur on real messages), and wires it
into MessageBubble.tsx (reusing the existing Image/File/Audio/Video
Attachment components) and preview.ts (matching bracket text). Extends
VideoAttachment with a remote `previewRef` fallback alongside its
existing inline-base64 `preview`, since mobile videos' poster is a
separately-hosted file, not inline data.

Verified live against the real message rows: detection and URL
construction are confirmed correct (network panel shows the real OSS-
backed URL, exactly matching the file_id from the DB row); the actual
pixels don't load in this local dev environment because OSS's CORS
whitelist doesn't include localhost, a known, already-documented
limitation of testing via localhost instead of a real *.118im.com
domain, not a defect in this fix.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

web/src/features/messages/MessageBubble.tsx

@@ -5,8 +5,17 @@ import { Link } from 'react-router-dom';
 import { Avatar } from '@/app/Avatar';
 import { Icon } from '@/app/Icon';
 import { SelectionCheckbox } from '@/app/SelectionCheckbox';
-import { callResultDisplay, contactCardContentOf, isRecalled, isServerDeleted, systemNoticeText, type ContactCardContent } from '@/lib/messages/dispatch';
+import {
+  callResultDisplay,
+  contactCardContentOf,
+  isRecalled,
+  isServerDeleted,
+  mobileAttachmentContentOf,
+  systemNoticeText,
+  type ContactCardContent,
+} from '@/lib/messages/dispatch';
 import { renderDrafty } from '@/lib/messages/drafty';
+import { AudioAttachment, FileAttachment, ImageAttachment, VideoAttachment } from '@/features/messages/AttachmentPreview';
 import { formatBubbleTime, formatEventTimestamp } from '@/lib/messages/time';
 import { isFailedStatus, isSendingStatus, outgoingStatusLabel } from '@/lib/messages/status';
 import { groupSenderLabel } from '@/lib/messages/sender-name';
@@ -111,6 +120,7 @@ export function MessageRow({
   const statusLabel = mine ? outgoingStatusLabel(topic, msg, isGroup) : msg.ts ? formatBubbleTime(msg.ts) : '';
   const callResult = callResultDisplay(msg, mine);
   const contactCard = contactCardContentOf(msg);
+  const mobileAttachment = mobileAttachmentContentOf(msg);
 
   const retry = () => {
     if (typeof msg.seq !== 'number') return;
@@ -200,6 +210,16 @@ export function MessageRow({
                 </span>
               ) : contactCard ? (
                 <ContactCardBubble content={contactCard} />
+              ) : mobileAttachment ? (
+                mobileAttachment.kind === 'image' ? (
+                  <ImageAttachment data={mobileAttachment} />
+                ) : mobileAttachment.kind === 'video' ? (
+                  <VideoAttachment data={{ ...mobileAttachment, previewRef: mobileAttachment.previewRef }} />
+                ) : mobileAttachment.kind === 'voice' ? (
+                  <AudioAttachment data={mobileAttachment} />
+                ) : (
+                  <FileAttachment data={mobileAttachment} />
+                )
               ) : (
                 renderDrafty(msg.content)
               )}