feat(screenshots): commit the image and PDF test fixtures

The specs reference six fixtures that .gitignore excluded, so a fresh
checkout could not run the harness: 'Q2 Project Proposal.pdf' is used by five
specs and 'Team Meeting Notes.pdf' by two.

Drops playwright/fixtures/pdfs/ and playwright/fixtures/images/ from
.gitignore, plus the dead cypress/fixtures/pdfs/ line left from before the
Playwright switch. playwright/results/ and playwright/.auth/ stay ignored:
both are generated, and .auth/state.json holds session cookies.

The four images are replacements sourced from Wikimedia Commons so the
licensing is explicit:

  city-night-purple.jpg  CC0-1.0        Wilfredor
  forest-green.jpg       CC0-1.0        Zed Can77
  milky-way.jpg          public domain  NASA/JPL-Caltech/S. Stolovy (Spitzer)
  ocean-golden.jpg       CC0-1.0        Bernard Spragg, NZ

The PDFs are generated, not third-party content.

AI-Assisted-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Signed-off-by: Anna Larch <anna@nextcloud.com>

Author: miaulalala

.gitignore

@@ -68,8 +68,5 @@ cypress/snapshots/
 cypress/videos/
 cypress/downloads/
 screenshot-inventory.json
-cypress/fixtures/pdfs/
 playwright/results/
 playwright/.auth/
-playwright/fixtures/pdfs/
-playwright/fixtures/images/