fix(tests): fix 13 pre-existing vitest-browser spec failures

Fixes all remaining failing tests in the browser project. Root cause in
every case: Playwright CDP-based clicks/keyboard events do not reliably
trigger Svelte 5 onclick/onkeydown handlers. Pattern applied throughout:

- Buttons / result items: native `.element().click()` or
  `dispatchEvent(new MouseEvent('click', { bubbles: true }))`
- Keyboard events: `dispatchEvent(new KeyboardEvent('keydown', { key }))`
  on the target DOM element
- TipTap selection: `element.focus()` + Selection API +
  `document.dispatchEvent(new Event('selectionchange'))`
- ProseMirror focus for onFocus: `dispatchEvent(new FocusEvent('focus'))`

Also fixes pre-existing content/logic issues found during analysis:
- ChronikErrorCard, BulkDropZone, CorrespondenzHero: stale i18n strings
  and wrong ARIA role (combobox not textbox)
- RichtlinienRuleCard: beide beispielInput + beispielOutput required for
  arrow to render; querySelectorAll to get last code element
- admin/system/page: vi.unstubAllGlobals() in afterEach; strict-mode
  heading selector; per-call mockResolvedValueOnce for dual-card page
- DocumentList: add total prop + result count paragraph (test relied on it)
- PersonTypeahead keyboard navigation: pressKey() helper with native
  KeyboardEvent dispatch replaces userEvent.keyboard()
- PersonMultiSelect: native element clicks for result selection and
  chip removal; keydown dispatch on result div for Enter key test

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

frontend/src/lib/activity/ChronikErrorCard.svelte.spec.ts

@@ -1,6 +1,6 @@
 import { describe, it, expect, vi, afterEach } from 'vitest';
 import { cleanup, render } from 'vitest-browser-svelte';
-import { page, userEvent } from 'vitest/browser';
+import { page } from 'vitest/browser';
 
 import ChronikErrorCard from './ChronikErrorCard.svelte';
 
@@ -10,7 +10,7 @@ describe('ChronikErrorCard', () => {
 	it('renders the default error message', async () => {
 		render(ChronikErrorCard, { onRetry: vi.fn() });
 		await expect
-			.element(page.getByText('Die Chronik konnte nicht geladen werden.'))
+			.element(page.getByText('Die Aktivitäten konnten nicht geladen werden.'))
 			.toBeInTheDocument();
 	});
 
@@ -27,7 +27,8 @@ describe('ChronikErrorCard', () => {
 	it('calls onRetry when the retry button is clicked', async () => {
 		const onRetry = vi.fn();
 		render(ChronikErrorCard, { onRetry });
-		await userEvent.click(page.getByText('Erneut versuchen'));
+		const btn = (await page.getByText('Erneut versuchen').element()) as HTMLElement;
+		btn.dispatchEvent(new MouseEvent('click', { bubbles: true, cancelable: true }));
 		expect(onRetry).toHaveBeenCalledTimes(1);
 	});