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.

src/components/common/RefreshButton.vue

@@ -1,52 +0,0 @@
-<!--
-  A refresh button that disables and shows a progress spinner whilst active.
-
-  Usage:
-  ```vue
-    <RefreshButton
-      v-model="isRefreshing"
-      :outlined="false"
-      @refresh="refresh"
-    />
-  ```
--->
-<template>
-  <Button
-    class="relative p-button-icon-only"
-    :outlined="outlined"
-    :severity="severity"
-    :disabled="active || disabled"
-    @click="(event) => $emit('refresh', event)"
-  >
-    <span
-      class="p-button-icon pi pi-refresh transition-all"
-      :class="{ 'opacity-0': active }"
-      data-pc-section="icon"
-    />
-    <span class="p-button-label" data-pc-section="label">&nbsp;</span>
-    <ProgressSpinner v-show="active" class="absolute w-1/2 h-1/2" />
-  </Button>
-</template>
-
-<script setup lang="ts">
-import Button from 'primevue/button'
-import ProgressSpinner from 'primevue/progressspinner'
-
-import type { PrimeVueSeverity } from '@/types/primeVueTypes'
-
-const {
-  disabled,
-  outlined = true,
-  severity = 'secondary'
-} = defineProps<{
-  disabled?: boolean
-  outlined?: boolean
-  severity?: PrimeVueSeverity
-}>()
-
-// Model
-const active = defineModel<boolean>({ required: true })
-
-// Emits
-defineEmits(['refresh'])
-</script>

src/components/common/StartupDisplay.vue

@@ -1,71 +0,0 @@
-<template>
-  <div :class="wrapperClass">
-    <div class="grid grid-rows-2 gap-8">
-      <!-- Top container: Logo -->
-      <div class="flex items-end justify-center">
-        <img
-          src="/assets/images/comfy-brand-mark.svg"
-          :alt="t('g.logoAlt')"
-          class="w-60"
-        />
-      </div>
-      <!-- Bottom container: Progress and text -->
-      <div class="flex flex-col items-center justify-center gap-4">
-        <ProgressBar
-          v-if="!hideProgress"
-          :mode="progressMode"
-          :value="progressPercentage ?? 0"
-          :show-value="false"
-          class="w-90 h-2 mt-8"
-          :pt="{ value: { class: 'bg-brand-yellow' } }"
-        />
-        <h1 v-if="title" class="font-inter font-bold text-3xl text-neutral-300">
-          {{ title }}
-        </h1>
-        <p v-if="statusText" class="text-lg text-neutral-400">
-          {{ statusText }}
-        </p>
-      </div>
-    </div>
-  </div>
-</template>
-
-<script setup lang="ts">
-import ProgressBar from 'primevue/progressbar'
-import { computed } from 'vue'
-import { useI18n } from 'vue-i18n'
-
-const { t } = useI18n()
-
-/** Props for the StartupDisplay component */
-interface StartupDisplayProps {
-  /** Progress: 0-100 for determinate, undefined for indeterminate */
-  progressPercentage?: number
-  /** Main title text */
-  title?: string
-  /** Status text shown below the title */
-  statusText?: string
-  /** Hide the progress bar */
-  hideProgress?: boolean
-  /** Use full screen wrapper (default: true) */
-  fullScreen?: boolean
-}
-
-const {
-  progressPercentage,
-  title,
-  statusText,
-  hideProgress = false,
-  fullScreen = true
-} = defineProps<StartupDisplayProps>()
-
-const progressMode = computed(() =>
-  progressPercentage === undefined ? 'indeterminate' : 'determinate'
-)
-
-const wrapperClass = computed(() =>
-  fullScreen
-    ? 'flex items-center justify-center min-h-screen'
-    : 'flex items-center justify-center'
-)
-</script>