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/install/HardwareOption.stories.ts

@@ -0,0 +1,73 @@
+// eslint-disable-next-line storybook/no-renderer-packages
+import type { Meta, StoryObj } from '@storybook/vue3'
+
+import HardwareOption from './HardwareOption.vue'
+
+const meta: Meta<typeof HardwareOption> = {
+  title: 'Desktop/Components/HardwareOption',
+  component: HardwareOption,
+  parameters: {
+    layout: 'centered',
+    backgrounds: {
+      default: 'dark',
+      values: [{ name: 'dark', value: '#1a1a1a' }]
+    }
+  },
+  argTypes: {
+    selected: { control: 'boolean' },
+    imagePath: { control: 'text' },
+    placeholderText: { control: 'text' },
+    subtitle: { control: 'text' }
+  }
+}
+
+export default meta
+type Story = StoryObj<typeof meta>
+
+export const AppleMetalSelected: Story = {
+  args: {
+    imagePath: '/assets/images/apple-mps-logo.png',
+    placeholderText: 'Apple Metal',
+    subtitle: 'Apple Metal',
+    value: 'mps',
+    selected: true
+  }
+}
+
+export const AppleMetalUnselected: Story = {
+  args: {
+    imagePath: '/assets/images/apple-mps-logo.png',
+    placeholderText: 'Apple Metal',
+    subtitle: 'Apple Metal',
+    value: 'mps',
+    selected: false
+  }
+}
+
+export const CPUOption: Story = {
+  args: {
+    placeholderText: 'CPU',
+    subtitle: 'Subtitle',
+    value: 'cpu',
+    selected: false
+  }
+}
+
+export const ManualInstall: Story = {
+  args: {
+    placeholderText: 'Manual Install',
+    subtitle: 'Subtitle',
+    value: 'unsupported',
+    selected: false
+  }
+}
+
+export const NvidiaSelected: Story = {
+  args: {
+    imagePath: '/assets/images/nvidia-logo-square.jpg',
+    placeholderText: 'NVIDIA',
+    subtitle: 'NVIDIA',
+    value: 'nvidia',
+    selected: true
+  }
+}