Decouple Desktop UI into monorepo app (#5912)

## Summary

Extracts desktop UI into apps/desktop-ui package with minimal changes.

## Changes

- **What**:
- Separates desktop-specific code into standalone package with
independent Vite config, router, and i18n
- Drastically simplifies the main app router by removing all desktop
routes
  - Adds a some code duplication, most due to the existing design
- Some duplication can be refactored to be *simpler* on either side - no
need to split things by `isElectron()`
  - Rudimentary storybook support has been added
- **Breaking**: Stacked PR for publishing must be merged before this PR
makes it to stable core (but publishing _could_ be done manually)
  - #5915
- **Dependencies**: Takes full advantage of pnpm catalog. No additional
dependencies added.

## Review Focus

- Should be no changes to normal frontend operation
- Scripts added to root package.json are acceptable
- The duplication in this PR is copied as is, wherever possible. Any
corrections or fix-ups beyond the scope of simply migrating the
functionality as-is, can be addressed in later PRs. That said, if any
changes are made, it instantly becomes more difficult to separate the
duplicated code out into a shared utility.
  - Tracking issue to address concerns: #5925

### i18n

Fixing i18n is out of scope for this PR. It is a larger task that we
should consider carefully and implement properly. Attempting to isolate
the desktop i18n and duplicate the _current_ localisation scripts would
be wasted energy.

apps/desktop-ui/src/views/DesktopDialogView.vue

@@ -0,0 +1,70 @@
+<template>
+  <div class="w-full h-full flex flex-col rounded-lg p-6 justify-between">
+    <h1 class="font-inter font-semibold text-xl m-0 italic">
+      {{ t(`desktopDialogs.${id}.title`, title) }}
+    </h1>
+    <p class="whitespace-pre-wrap">
+      {{ t(`desktopDialogs.${id}.message`, message) }}
+    </p>
+    <div class="flex w-full gap-2">
+      <Button
+        v-for="button in buttons"
+        :key="button.label"
+        class="rounded-lg first:mr-auto"
+        :label="
+          t(
+            `desktopDialogs.${id}.buttons.${normalizeI18nKey(button.label)}`,
+            button.label
+          )
+        "
+        :severity="button.severity ?? 'secondary'"
+        @click="handleButtonClick(button)"
+      />
+    </div>
+  </div>
+</template>
+
+<script setup lang="ts">
+import { normalizeI18nKey } from '@comfyorg/shared-frontend-utils/formatUtil'
+import Button from 'primevue/button'
+import { useRoute } from 'vue-router'
+
+import { type DialogAction, getDialog } from '@/constants/desktopDialogs'
+import { t } from '@/i18n'
+import { electronAPI } from '@/utils/envUtil'
+
+const route = useRoute()
+const { id, title, message, buttons } = getDialog(route.params.dialogId)
+
+const handleButtonClick = async (button: DialogAction) => {
+  await electronAPI().Dialog.clickButton(button.returnValue)
+}
+</script>
+
+<style scoped>
+@reference '../assets/css/style.css';
+
+.p-button-secondary {
+  @apply text-white border-none bg-neutral-600;
+}
+
+.p-button-secondary:hover {
+  @apply bg-neutral-550;
+}
+
+.p-button-secondary:active {
+  @apply bg-neutral-500;
+}
+
+.p-button-danger {
+  @apply bg-coral-red-600;
+}
+
+.p-button-danger:hover {
+  @apply bg-coral-red-500;
+}
+
+.p-button-danger:active {
+  @apply bg-coral-red-400;
+}
+</style>