Fix the slider pause label and three contrast findings in 1.12.1

Lighthouse and axe on the Elektro Bernhard site: the slider pause button
had visible text "Pause" but an accessible name that did not contain it
(WCAG 2.5.3); the name now starts with the visible text. On the site the
brand names and the footer credit link lacked contrast and the services
page jumped from H1 to H3. After the fixes: axe zero violations on six
pages, Lighthouse 100 everywhere except mobile home performance 99.
Measurements documented in docs/QUALITY.md.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

scripts/admin-quality-check.mjs

@@ -72,11 +72,11 @@ try {
   await page.mouse.move(1, 1); await page.waitForTimeout(7200);
   console.log('Paused slider:', JSON.stringify(await geometry()), await controls.innerText());
   assert.ok(Math.abs((await geometry()).left - manual.left) < 2, 'manual navigation pauses autoplay');
-  await controls.getByRole('button', { name: 'Automatische Wiedergabe starten' }).click();
+  await controls.getByRole('button', { name: 'Wiedergabe: automatisch weiterblättern' }).click();
   await page.mouse.move(1, 1); await page.waitForTimeout(7700);
   assert.ok(Math.abs((await geometry()).left - manual.left) > 20, 'play resumes after manual operation');
   await page.emulateMedia({ reducedMotion: 'reduce' });
-  assert.equal(await controls.getByRole('button', { name: 'Automatische Wiedergabe starten' }).isDisabled(), true);
+  assert.equal(await controls.getByRole('button', { name: 'Wiedergabe: automatisch weiterblättern' }).isDisabled(), true);
   const reduced = await geometry(); await page.waitForTimeout(7100);
   assert.ok(Math.abs((await geometry()).left - reduced.left) < 2, 'reduced motion stops autoplay');
   await controls.getByRole('button', { name: 'Vorherige Folie', exact: true }).click();