fix(admin): theme, American English, and inventory/reservation tooling (#27)

Seven reported items, of which the first four had two root causes.

The active tab was invisible in dark mode because colorPrimary was
hardcoded to #1a1a1a in both themes. The accent now inverts with the
theme, and colorTextLightSolid inverts with it, or a near-white accent
would get antd's default white label and disappear.

The Category tab, Tag tab, and item-form category selector ignored the
theme entirely. antd declares main: lib/index.js and module: es/index.js,
so importing from 'antd' resolves to the ES build while 'antd/lib/...'
loads the CommonJS one — two copies, two React contexts, and no
ConfigProvider for anything deep-imported. Switching those files to
antd/es/* keeps the deep-import convention and shares the instance. This
was introduced by my own use of the lib path; es is correct under Vite.
Two storefront components had the same latent bug.

"Colour" is now "Color".

The Customers tab shows how many items each customer is holding, as a
link opening the item list with a Release button. Release mirrors the
customer's own cart removal — drop the cart row, return the item to
available, guarded on 'reserved' so it can never resurrect a sold item —
and deliberately sends no email about an action the customer did not
take. The count is a subquery rather than another join, which would have
multiplied rows and inflated order_count and total_spent_cents.

The Inventory tab filters by category, tags, price, and status, reusing
the storefront's parser and query builder so the two cannot drift.
Reserved is one option in a Status filter rather than a standalone toggle.

Also fixes two defects the screenshots exposed: the reserved-count link
bubbled to the row handler and opened the customer drawer behind the
dialog, and .admin-category-node had no CSS at all, so the tree node name,
item count, and actions ran together as one string.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

frontend/tests/e2e/admin-reserved-items.spec.ts

@@ -0,0 +1,94 @@
+import { test, expect } from '@playwright/test';
+
+const suffix = () => `r${Date.now().toString(36)}${Math.random().toString(36).slice(2, 7)}`;
+
+// Reserves an item by registering a customer and adding it to their cart, which
+// is the only way an item legitimately reaches 'reserved'.
+async function reserveItem(page: import('@playwright/test').Page, itemName: string) {
+  const email = `reserve-${suffix()}@example.com`;
+
+  const created = await page.request.post('/api/admin/items', {
+    multipart: { name: itemName, description: '', price: '75', category_id: '', tags: '[]' }
+  });
+  expect(created.ok()).toBeTruthy();
+  const itemId = (await created.json()).id as number;
+
+  await page.goto('/register');
+  await page.getByRole('textbox', { name: 'Email' }).fill(email);
+  await page.getByLabel('Password').fill('supersecret123');
+  await page.getByRole('button', { name: 'Create account' }).click();
+  await expect(page).toHaveURL(/\/account/);
+
+  const added = await page.request.post(`/api/cart/items/${itemId}`);
+  expect(added.status()).toBe(201);
+
+  return { email, itemId };
+}
+
+test.describe('Admin reserved items', () => {
+  test('shows a reserved count that opens the held items', async ({ page }) => {
+    const itemName = `Held ${suffix()}`;
+    const { email } = await reserveItem(page, itemName);
+
+    await page.goto('/admin');
+    await page.getByRole('tab', { name: 'Customers' }).click();
+
+    const row = page.getByRole('row').filter({ hasText: email });
+    await expect(row).toBeVisible();
+    await row.getByRole('button', { name: /item/ }).click();
+
+    const dialog = page.getByRole('dialog', { name: /Items reserved by/ });
+    await expect(dialog.getByText(itemName)).toBeVisible();
+  });
+
+  test('releasing an item returns it to the storefront as available', async ({ page }) => {
+    const itemName = `Freed ${suffix()}`;
+    const { email, itemId } = await reserveItem(page, itemName);
+
+    await page.goto('/admin');
+    await page.getByRole('tab', { name: 'Customers' }).click();
+    const row = page.getByRole('row').filter({ hasText: email });
+    await row.getByRole('button', { name: /item/ }).click();
+
+    const dialog = page.getByRole('dialog', { name: /Items reserved by/ });
+    await dialog.getByRole('button', { name: 'Release' }).click();
+    await expect(page.getByText(`Released "${itemName}"`)).toBeVisible();
+
+    // The point of releasing is that the item becomes purchasable again.
+    const item = await (await page.request.get(`/api/items/${itemId}`)).json();
+    expect(item.status).toBe('available');
+  });
+
+  test('the count drops once the item is released', async ({ page }) => {
+    const itemName = `Recount ${suffix()}`;
+    const { email } = await reserveItem(page, itemName);
+
+    await page.goto('/admin');
+    await page.getByRole('tab', { name: 'Customers' }).click();
+    const row = page.getByRole('row').filter({ hasText: email });
+    await row.getByRole('button', { name: /item/ }).click();
+
+    const dialog = page.getByRole('dialog', { name: /Items reserved by/ });
+    await dialog.getByRole('button', { name: 'Release' }).click();
+    await expect(dialog.getByText("This customer isn't holding any items")).toBeVisible();
+
+    // The row behind the dialog must agree with the dialog it opened.
+    await dialog.getByRole('button', { name: 'Close' }).click();
+    await expect(row.getByRole('button', { name: /item/ })).toHaveCount(0);
+  });
+
+  test('a customer holding nothing shows no link to click', async ({ page }) => {
+    const email = `idle-${suffix()}@example.com`;
+    await page.goto('/register');
+    await page.getByRole('textbox', { name: 'Email' }).fill(email);
+    await page.getByLabel('Password').fill('supersecret123');
+    await page.getByRole('button', { name: 'Create account' }).click();
+    await expect(page).toHaveURL(/\/account/);
+
+    await page.goto('/admin');
+    await page.getByRole('tab', { name: 'Customers' }).click();
+    const row = page.getByRole('row').filter({ hasText: email });
+    await expect(row).toBeVisible();
+    await expect(row.getByRole('button', { name: /item/ })).toHaveCount(0);
+  });
+});