merge: bring gallery frontend branch up to date with goutamnextflow

goutamnextflow adopts @insignia/iios-messaging-ui (drops the bespoke
messenger/inbox/mail) and adds Org Settings → Integrations. Resolve against
the Smart Gallery work:
- dashboard.tsx: route messenger→MessengerSdk, inbox→InboxSdk, add settings→
  Settings (goutamnextflow) AND keep gallery→SmartGallery (ours). Drop the
  now-deleted Messenger/Inbox imports.
- next.config.ts / package.json: union transpilePackages + deps (keep
  @photo-gallery/sdk + ML deps AND @insignia/iios-messaging-ui).
- dashboard.css: keep both appended blocks (.gal* gallery + .settings-* org
  settings).

Gallery integrates with zero errors. Vendored @photo-gallery/sdk re-synced
(0-diff). Verified: tsc clean + `next build` compiles the whole merged app
(gallery AI routes + dashboard). The new @insignia/iios-messaging-ui private
dep is stubbed locally (see .claude/dev-scripts); it resolves on CI/Vercel.

package.json

@@ -14,6 +14,7 @@
     "@huggingface/transformers": "^4.2.0",
     "@imgly/background-removal": "^1.7.0",
     "@insignia/iios-kernel-client": "^0.1.4",
+    "@insignia/iios-messaging-ui": "^0.1.4",
     "@photo-gallery/sdk": "file:./vendor/photo-gallery-sdk",
     "@tensorflow-models/coco-ssd": "^2.2.3",
     "@tensorflow/tfjs": "^4.22.0",