chore: add missing i18n keys in sidebar, assets, toolbox, dropdowns (#6622)

This PR 

- adds missing locale keys for 3D viewer toast strings, assets sidebar
labels, and node error keys
- cleans up the selection toolbox, media previews, node components, and
widget uploader to rely on `$t`/`st` (exposed to template scope at
compile time) instead of importing from `useI18n`.
- updates `eslint.config.ts` to teach the Intlify rule about the locale
layout

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6622-chore-add-missing-i18n-keys-in-sidebar-assets-toolbox-dropdowns-2a36d73d365081ae8694eb4f8ebb822a)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Alexander Brown <drjkl@comfy.org>

src/platform/assets/components/Media3DTop.vue

@@ -7,10 +7,8 @@
         class="icon-[lucide--box] text-3xl text-zinc-600 dark-theme:text-zinc-200"
       />
       <span class="text-zinc-600 dark-theme:text-zinc-200">{{
-        $t('3D Model')
+        $t('assetBrowser.media.threeDModelPlaceholder')
       }}</span>
     </div>
   </div>
 </template>
-
-<script setup lang="ts"></script>

src/platform/assets/components/MediaAudioTop.vue

@@ -7,7 +7,7 @@
         class="icon-[lucide--music] text-3xl text-zinc-600 dark-theme:text-zinc-200"
       />
       <span class="text-zinc-600 dark-theme:text-zinc-200">{{
-        $t('Audio')
+        $t('assetBrowser.media.audioPlaceholder')
       }}</span>
     </div>
     <audio