feat(messaging-ui): Attachment carries contentRef + sizeBytes for messenger media (0.1.4)

Extend the messaging Attachment type with optional storage fields so an adapter's
upload() can return a sendable reference (the socket needs contentRef/mimeType/
sizeBytes to persist the message part) while keeping the display url. Enables
messenger attachments end-to-end in host adapters.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packages/iios-messaging-ui/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@insignia/iios-messaging-ui",
-  "version": "0.1.3",
+  "version": "0.1.4",
   "type": "module",
   "main": "dist/index.js",
   "module": "dist/index.js",