test(e2e): rewrite PDF viewer and annotation beforeAll to use API calls

- Replace UI-based document setup in beforeAll hooks with direct API
  calls via Playwright's request fixture — avoids the 90s timeout from
  navigating + uploading through the Docker dev server
- Fix non-PDF test: create a file-less document in beforeAll instead of
  relying on seed data that may not exist
- Share annotationDocId across describe blocks so the read-only user
  test can navigate to a known PDF document
- Add annotation visibility check before enabling annotate mode in the
  delete test

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

frontend/e2e/.auth/user.json

@@ -5,7 +5,7 @@
       "value": "de",
       "domain": "localhost",
       "path": "/",
-      "expires": 1808565334.192108,
+      "expires": 1808896929.897686,
       "httpOnly": false,
       "secure": false,
       "sameSite": "Lax"
@@ -15,7 +15,7 @@
       "value": "Basic%20YWRtaW46YWRtaW4xMjM%3D",
       "domain": "localhost",
       "path": "/",
-      "expires": 1774091734.449243,
+      "expires": 1774423330.233039,
       "httpOnly": true,
       "secure": false,
       "sameSite": "Strict"