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/components/widget/SampleModelSelector.vue

@@ -1,12 +1,12 @@
 <template>
-  <BaseModalLayout :content-title="$t('Checkpoints')">
+  <BaseModalLayout :content-title="$t('assetBrowser.checkpoints')">
     <template #leftPanel>
       <LeftSidePanel v-model="selectedNavItem" :nav-items="tempNavigation">
         <template #header-icon>
           <i class="text-neutral icon-[lucide--puzzle]" />
         </template>
         <template #header-title>
-          <span class="text-neutral text-base">{{ t('g.title') }}</span>
+          <span class="text-neutral text-base">{{ $t('g.title') }}</span>
         </template>
       </LeftSidePanel>
     </template>
@@ -132,7 +132,6 @@
 
 <script setup lang="ts">
 import { computed, provide, ref } from 'vue'
-import { useI18n } from 'vue-i18n'
 
 import IconButton from '@/components/button/IconButton.vue'
 import IconTextButton from '@/components/button/IconTextButton.vue'
@@ -189,8 +188,6 @@ const tempNavigation = ref<(NavItemData | NavGroupData)[]>([
   }
 ])
 
-const { t } = useI18n()
-
 const { onClose } = defineProps<{
   onClose: () => void
 }>()