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/components/common/RefreshButton.vue

@@ -0,0 +1,52 @@
+<!--
+  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>

apps/desktop-ui/src/components/common/StartupDisplay.vue

@@ -0,0 +1,71 @@
+<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>

apps/desktop-ui/src/components/common/UrlInput.vue

@@ -0,0 +1,129 @@
+<template>
+  <IconField class="w-full">
+    <InputText
+      v-bind="$attrs"
+      :model-value="internalValue"
+      class="w-full"
+      :invalid="validationState === ValidationState.INVALID"
+      @update:model-value="handleInput"
+      @blur="handleBlur"
+    />
+    <InputIcon
+      :class="{
+        'pi pi-spin pi-spinner text-neutral-400':
+          validationState === ValidationState.LOADING,
+        'pi pi-check text-green-500 cursor-pointer':
+          validationState === ValidationState.VALID,
+        'pi pi-times text-red-500 cursor-pointer':
+          validationState === ValidationState.INVALID
+      }"
+      @click="validateUrl(props.modelValue)"
+    />
+  </IconField>
+</template>
+
+<script setup lang="ts">
+import { isValidUrl } from '@comfyorg/shared-frontend-utils/formatUtil'
+import { checkUrlReachable } from '@comfyorg/shared-frontend-utils/networkUtil'
+import IconField from 'primevue/iconfield'
+import InputIcon from 'primevue/inputicon'
+import InputText from 'primevue/inputtext'
+import { onMounted, ref, watch } from 'vue'
+
+import { ValidationState } from '@/utils/validationUtil'
+
+const props = defineProps<{
+  modelValue: string
+  validateUrlFn?: (url: string) => Promise<boolean>
+}>()
+
+const emit = defineEmits<{
+  'update:modelValue': [value: string]
+  'state-change': [state: ValidationState]
+}>()
+
+const validationState = ref<ValidationState>(ValidationState.IDLE)
+
+const cleanInput = (value: string): string =>
+  value ? value.replace(/\s+/g, '') : ''
+
+// Add internal value state
+const internalValue = ref(cleanInput(props.modelValue))
+
+// Watch for external modelValue changes
+watch(
+  () => props.modelValue,
+  async (newValue: string) => {
+    internalValue.value = cleanInput(newValue)
+    await validateUrl(newValue)
+  }
+)
+
+watch(validationState, (newState) => {
+  emit('state-change', newState)
+})
+
+// Validate on mount
+onMounted(async () => {
+  await validateUrl(props.modelValue)
+})
+
+const handleInput = (value: string | undefined) => {
+  // Update internal value without emitting
+  internalValue.value = cleanInput(value ?? '')
+  // Reset validation state when user types
+  validationState.value = ValidationState.IDLE
+}
+
+const handleBlur = async () => {
+  const input = cleanInput(internalValue.value)
+
+  let normalizedUrl = input
+  try {
+    const url = new URL(input)
+    normalizedUrl = url.toString()
+  } catch {
+    // If URL parsing fails, just use the cleaned input
+  }
+
+  // Emit the update only on blur
+  emit('update:modelValue', normalizedUrl)
+}
+
+// Default validation implementation
+const defaultValidateUrl = async (url: string): Promise<boolean> => {
+  if (!isValidUrl(url)) return false
+  try {
+    return await checkUrlReachable(url)
+  } catch {
+    return false
+  }
+}
+
+const validateUrl = async (value: string) => {
+  if (validationState.value === ValidationState.LOADING) return
+
+  const url = cleanInput(value)
+
+  // Reset state
+  validationState.value = ValidationState.IDLE
+
+  // Skip validation if empty
+  if (!url) return
+
+  validationState.value = ValidationState.LOADING
+  try {
+    const isValid = await (props.validateUrlFn ?? defaultValidateUrl)(url)
+    validationState.value = isValid
+      ? ValidationState.VALID
+      : ValidationState.INVALID
+  } catch {
+    validationState.value = ValidationState.INVALID
+  }
+}
+
+// Add inheritAttrs option to prevent attrs from being applied to root element
+defineOptions({
+  inheritAttrs: false
+})
+</script>