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/graph/selectionToolbox/DeleteButton.vue

@@ -2,7 +2,7 @@
   <Button
     v-show="isDeletable"
     v-tooltip.top="{
-      value: t('commands.Comfy_Canvas_DeleteSelectedItems.label'),
+      value: $t('commands.Comfy_Canvas_DeleteSelectedItems.label'),
       showDelay: 1000
     }"
     severity="secondary"
@@ -17,13 +17,11 @@
 <script setup lang="ts">
 import Button from 'primevue/button'
 import { computed } from 'vue'
-import { useI18n } from 'vue-i18n'
 
 import { useSelectionState } from '@/composables/graph/useSelectionState'
 import type { Positionable } from '@/lib/litegraph/src/interfaces'
 import { useCommandStore } from '@/stores/commandStore'
 
-const { t } = useI18n()
 const commandStore = useCommandStore()
 const { selectedItems } = useSelectionState()