test(person): add PersonChip browser tests

Covers the abbreviated/full name branches, the firstName-null fallback
path, link href derivation from person id, initials rendering, and the
deterministic avatar palette colour. Six tests, six branches hit.

Refs #496.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/lib/person/PersonChip.svelte.test.ts

@@ -0,0 +1,62 @@
+import { describe, it, expect, afterEach } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page } from 'vitest/browser';
+import PersonChip from './PersonChip.svelte';
+
+afterEach(cleanup);
+
+const personWithFirstName = {
+	id: 'p-1',
+	firstName: 'Helene',
+	lastName: 'Schmidt',
+	displayName: 'Helene Schmidt'
+};
+
+const personLastNameOnly = {
+	id: 'p-2',
+	firstName: null,
+	lastName: 'Müller',
+	displayName: 'Müller'
+};
+
+describe('PersonChip', () => {
+	it('renders the full display name when abbreviated is false', async () => {
+		render(PersonChip, { props: { person: personWithFirstName, abbreviated: false } });
+
+		await expect.element(page.getByText('Helene Schmidt')).toBeVisible();
+	});
+
+	it('renders the abbreviated name when abbreviated is true', async () => {
+		render(PersonChip, { props: { person: personWithFirstName, abbreviated: true } });
+
+		await expect.element(page.getByText('H. Schmidt')).toBeVisible();
+	});
+
+	it('falls back to lastName-only when the person has no firstName', async () => {
+		render(PersonChip, { props: { person: personLastNameOnly, abbreviated: true } });
+
+		await expect.element(page.getByText('Müller')).toBeVisible();
+	});
+
+	it('links to the person detail route by id', async () => {
+		render(PersonChip, { props: { person: personWithFirstName, abbreviated: false } });
+
+		await expect
+			.element(page.getByRole('link', { name: /helene schmidt/i }))
+			.toHaveAttribute('href', '/persons/p-1');
+	});
+
+	it('renders initials inside the avatar circle', async () => {
+		render(PersonChip, { props: { person: personWithFirstName, abbreviated: false } });
+
+		await expect.element(page.getByText('HS')).toBeVisible();
+	});
+
+	it('uses a deterministic avatar background color derived from the person id', async () => {
+		render(PersonChip, { props: { person: personWithFirstName, abbreviated: false } });
+
+		const initials = await page.getByText('HS').element();
+		const style = (initials as HTMLElement).getAttribute('style') ?? '';
+		expect(style).toMatch(/background-color:\s*(rgb\(|#)/i);
+	});
+});