feat(desktop): port the 15 design-system primitives (#14)

Verbatim port of the handoff primitives into components/ui/ — Icon,
Button, IconButton, Badge, Tag, Card, Tabs (core); Input, Select,
Checkbox, Radio, Switch (forms); Dialog, Toast, Tooltip (feedback).
Each keeps its injected token-referencing CSS byte-for-byte; the
handoff .d.ts contracts become the exported prop interfaces. Barrel at
components/ui/index.ts.

Adds a PrimitivesGallery (app root for now; real shell is P3-2) that
exercises every primitive with a light/dark toggle. Smoke suite asserts
the gallery, section coverage, theme flip, and dialog open/Escape;
screenshots captured for both themes. typecheck + 5 e2e green.

Closes P3-1.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/desktop/e2e/smoke.spec.ts

@@ -1,15 +1,33 @@
 import { expect, test } from './fixtures.js'
 
-test('boots and renders the CommiTea shell', async ({ app }) => {
-  await app.expectLoaded()
-  await app.screenshot('boot')
+test('boots and renders the primitives gallery', async ({ app, window }) => {
+  await expect(window.getByRole('heading', { name: 'Primitives' })).toBeVisible()
+  await expect(window.getByRole('button', { name: 'Brew plan' })).toBeVisible()
+  await app.screenshot('primitives-light')
 })
 
-test('renders the label-parse check from @commitea/core', async ({ window }) => {
-  // Proves the core package is bundled + running in the renderer, not just
-  // that the window opened. Updates as the scaffold gives way to real screens.
-  await expect(window.getByText(/label parse check/i)).toBeVisible()
-  await expect(window.getByText(/est\/3d · p\/2 · hard true/)).toBeVisible()
+test('primitives cover core, forms, and feedback', async ({ window }) => {
+  // section headings prove each cluster ported and rendered
+  for (const section of ['Button', 'Badge', 'Tag', 'Card', 'Input & Select', 'Feedback']) {
+    await expect(window.getByRole('heading', { name: section, exact: true })).toBeVisible()
+  }
+  // a mono label chip renders verbatim
+  await expect(window.getByText('deadline/hard')).toBeVisible()
+})
+
+test('dark theme toggle flips the document theme', async ({ app, window }) => {
+  await window.getByRole('button', { name: 'Switch to dark' }).click()
+  await expect(window.locator('html')).toHaveAttribute('data-theme', 'dark')
+  await app.screenshot('primitives-dark')
+})
+
+test('dialog opens on demand and closes on Escape', async ({ window }) => {
+  await window.getByRole('button', { name: 'Open dialog' }).click()
+  const dialog = window.getByRole('dialog')
+  await expect(dialog).toBeVisible()
+  await expect(dialog.getByText('Withdraw directive?')).toBeVisible()
+  await window.keyboard.press('Escape')
+  await expect(dialog).toBeHidden()
 })
 
 test('exposes the commitea preload API', async ({ app }) => {