Fix inline email images showing twice (once in the body, once as a chip)

An inline image referenced via cid: is already rendered inside message.bodyHtml
(added in the previous commit) but was also still stored as a regular
attachment row, so it showed up a second time as an AttachmentChip thumbnail
underneath the message — the images at top were correct, the small chips
below were a duplicate of the same image.

AttachmentDTO now carries isInline (true when the attachment's contentId is
set), and the message thread — both the admin ticket view and the customer
portal — filters those out of the separate attachment-chip list. Verified
against a live inbound message with a cid-referenced image: previously
rendered as both an <img> and an <a>-wrapped chip, now only the <img>.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GteWhnWKTmnXcsd5jx6H7u

src/app/(admin)/tickets/[id]/ticket-thread.tsx

@@ -333,9 +333,11 @@ function MessageBubble({ message }: { message: MessageDTO }) {
         ) : (
           <p className="mb-1 whitespace-pre-wrap text-sm">{message.body}</p>
         )}
-        {message.attachments.map((a) => (
-          <AttachmentChip key={a.id} attachment={a} />
-        ))}
+        {message.attachments
+          .filter((a) => !a.isInline)
+          .map((a) => (
+            <AttachmentChip key={a.id} attachment={a} />
+          ))}
         <p className="text-[11px] text-warning-soft-text/80">
           {message.authorName} · {formatRelativeTime(message.createdAt)}
         </p>
@@ -357,9 +359,11 @@ function MessageBubble({ message }: { message: MessageDTO }) {
         ) : (
           <p className="mb-1 whitespace-pre-wrap">{message.body}</p>
         )}
-        {message.attachments.map((a) => (
-          <AttachmentChip key={a.id} attachment={a} />
-        ))}
+        {message.attachments
+          .filter((a) => !a.isInline)
+          .map((a) => (
+            <AttachmentChip key={a.id} attachment={a} />
+          ))}
         <p className={`text-[11px] ${isAgent ? "text-white/70" : "text-text-faint"}`}>
           {message.authorName} · {formatRelativeTime(message.createdAt)}
         </p>