fix(tests): fix 3 pre-existing vitest-browser spec failures

Three distinct root causes:

1. hilfe/transkription: Wikipedia link test was checking .textContent but
   the accessible text had moved to aria-label in a prior commit.

2. documents/[id]/edit: vi.spyOn on a Svelte 5 compiled .svelte.ts service
   object does not reliably track calls in vitest-browser mode; replaced
   with a plain closure-based mock.

3. GeschichteEditor: TipTap's onMount steals focus and its ProseMirror
   view interferes with Playwright CDP event dispatch. Three workarounds:
   - blur: dispatchEvent(new FocusEvent('blur')) bypasses focus-state check
   - save buttons: dispatchEvent(new MouseEvent('click')) from in-browser JS
     context reliably triggers Svelte 5 onclick vs. Playwright CDP click
   - trailing-space fill: input.value + dispatchEvent('input') works where
     userEvent.fill('value ') silently fails to update bind:value

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

frontend/src/routes/hilfe/transkription/page.svelte.spec.ts

@@ -25,9 +25,9 @@ describe('Richtlinien page — structure', () => {
 		await expect.element(wikiLink).toHaveAttribute('target', '_blank');
 		await expect.element(wikiLink).toHaveAttribute('rel', 'noopener noreferrer');
 		await expect.element(wikiLink).toHaveAttribute('referrerpolicy', 'no-referrer');
-		// visible annotation (not sr-only)
+		// icon communicates "opens new tab" visually; aria-label carries the text for a11y
 		const link = document.querySelector('a[href*="wikipedia"]') as HTMLAnchorElement;
-		expect(link.textContent).toContain('öffnet in neuem Tab');
+		expect(link.getAttribute('aria-label')).toContain('öffnet in neuem Tab');
 	});
 
 	it('renders Regeln h2 section', async () => {