feat(geschichten): chip-row UI for multi-person AND filter

The /geschichten list page now renders one removable chip per active
person filter and lets users add more via the existing typeahead. The
URL uses repeated ?personId= params (matching the documents tag
filter), which the regenerated API client passes straight through to
the backend's new array-bound endpoint. New translation keys cover the
chip remove aria-label, the AND hint shown while picking, and the
multi-person empty state.

frontend/src/routes/geschichten/page.svelte.spec.ts

@@ -0,0 +1,102 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page } from 'vitest/browser';
+
+vi.mock('$app/navigation', () => ({ goto: vi.fn() }));
+vi.mock('$app/state', () => ({ navigating: { to: null } }));
+
+import Page from './+page.svelte';
+import type { PageData } from './$types';
+
+afterEach(() => {
+	cleanup();
+	vi.clearAllMocks();
+});
+
+function person(id: string, displayName: string) {
+	return {
+		id,
+		firstName: displayName.split(' ')[0] ?? displayName,
+		lastName: displayName.split(' ').slice(1).join(' ') || 'X',
+		displayName,
+		personType: 'PERSON'
+	};
+}
+
+function makeData(overrides: Partial<PageData> = {}): PageData {
+	return {
+		geschichten: [],
+		personFilters: [],
+		documentFilter: null,
+		canBlogWrite: false,
+		...overrides
+	} as unknown as PageData;
+}
+
+describe('geschichten page — multi-person filter chips', () => {
+	it('renders one chip per person in personFilters', async () => {
+		render(Page, {
+			data: makeData({
+				personFilters: [person('a', 'Anna A'), person('b', 'Bertha B')] as PageData['personFilters']
+			})
+		});
+
+		await expect
+			.element(page.getByRole('button', { name: /Anna A aus Filter entfernen/ }))
+			.toBeVisible();
+		await expect
+			.element(page.getByRole('button', { name: /Bertha B aus Filter entfernen/ }))
+			.toBeVisible();
+	});
+
+	it('renders the "All" pill in pressed state when no filters are active', async () => {
+		render(Page, { data: makeData() });
+		await expect
+			.element(page.getByRole('button', { name: 'Alle' }))
+			.toHaveAttribute('aria-pressed', 'true');
+	});
+
+	it('renders the "All" pill in unpressed state when at least one filter is active', async () => {
+		render(Page, {
+			data: makeData({
+				personFilters: [person('a', 'Anna A')] as PageData['personFilters']
+			})
+		});
+		await expect
+			.element(page.getByRole('button', { name: 'Alle' }))
+			.toHaveAttribute('aria-pressed', 'false');
+	});
+
+	it('clicking × on a chip removes only that person from the URL', async () => {
+		const { goto } = await import('$app/navigation');
+		vi.mocked(goto).mockClear();
+
+		// Seed window.location so the chip-removal logic builds the new URL deterministically.
+		const originalHref = window.location.href;
+		window.history.replaceState({}, '', '/geschichten?personId=a&personId=b');
+
+		render(Page, {
+			data: makeData({
+				personFilters: [person('a', 'Anna A'), person('b', 'Bertha B')] as PageData['personFilters']
+			})
+		});
+
+		await page.getByRole('button', { name: /Anna A aus Filter entfernen/ }).click();
+
+		expect(goto).toHaveBeenCalledOnce();
+		const url = vi.mocked(goto).mock.calls[0][0] as string;
+		expect(url).toContain('personId=b');
+		expect(url).not.toContain('personId=a');
+
+		window.history.replaceState({}, '', originalHref);
+	});
+
+	it('shows the "+ Person wählen" button even when filters are already active', async () => {
+		render(Page, {
+			data: makeData({
+				personFilters: [person('a', 'Anna A')] as PageData['personFilters']
+			})
+		});
+		await expect.element(page.getByRole('button', { name: /Person wählen/ })).toBeVisible();
+	});
+});