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/maintenance/TaskListPanel.vue

@@ -0,0 +1,115 @@
+<template>
+  <!-- Tasks -->
+  <section class="my-4">
+    <template v-if="filter.tasks.length === 0">
+      <!-- Empty filter -->
+      <Divider />
+      <p class="text-neutral-400 w-full text-center">
+        {{ $t('maintenance.allOk') }}
+      </p>
+    </template>
+
+    <template v-else>
+      <!-- Display: List -->
+      <table
+        v-if="displayAsList === PrimeIcons.LIST"
+        class="w-full border-collapse border-hidden"
+      >
+        <TaskListItem
+          v-for="task in filter.tasks"
+          :key="task.id"
+          :task
+          @execute="(event) => confirmButton(event, task)"
+        />
+      </table>
+
+      <!-- Display: Cards -->
+      <template v-else>
+        <div class="flex flex-wrap justify-evenly gap-8 pad-y my-4">
+          <TaskCard
+            v-for="task in filter.tasks"
+            :key="task.id"
+            :task
+            @execute="(event) => confirmButton(event, task)"
+          />
+        </div>
+      </template>
+    </template>
+    <ConfirmPopup />
+  </section>
+</template>
+
+<script setup lang="ts">
+import { PrimeIcons } from '@primevue/core/api'
+import { useConfirm, useToast } from 'primevue'
+import ConfirmPopup from 'primevue/confirmpopup'
+import Divider from 'primevue/divider'
+
+import { t } from '@/i18n'
+import { useMaintenanceTaskStore } from '@/stores/maintenanceTaskStore'
+import type {
+  MaintenanceFilter,
+  MaintenanceTask
+} from '@/types/desktop/maintenanceTypes'
+
+import TaskCard from './TaskCard.vue'
+import TaskListItem from './TaskListItem.vue'
+
+const toast = useToast()
+const confirm = useConfirm()
+const taskStore = useMaintenanceTaskStore()
+
+// Properties
+defineProps<{
+  displayAsList: string
+  filter: MaintenanceFilter
+  isRefreshing: boolean
+}>()
+
+const executeTask = async (task: MaintenanceTask) => {
+  let message: string | undefined
+
+  try {
+    // Success
+    if ((await taskStore.execute(task)) === true) return
+
+    message = t('maintenance.error.taskFailed')
+  } catch (error) {
+    message = (error as Error)?.message
+  }
+
+  toast.add({
+    severity: 'error',
+    summary: t('maintenance.error.toastTitle'),
+    detail: message ?? t('maintenance.error.defaultDescription'),
+    life: 10_000
+  })
+}
+
+// Commands
+const confirmButton = async (event: MouseEvent, task: MaintenanceTask) => {
+  if (!task.requireConfirm) {
+    await executeTask(task)
+    return
+  }
+
+  confirm.require({
+    target: event.currentTarget as HTMLElement,
+    message: task.confirmText ?? t('maintenance.confirmTitle'),
+    icon: 'pi pi-exclamation-circle',
+    rejectProps: {
+      label: t('g.cancel'),
+      severity: 'secondary',
+      outlined: true
+    },
+    acceptProps: {
+      label: task.button?.text ?? t('g.save'),
+      severity: task.severity ?? 'primary'
+    },
+    // TODO: Not awaited.
+    accept: async () => {
+      await executeTask(task)
+    }
+  })
+}
+</script>