Fix paths in ui-e2e-test-pr-cluster job

Fix three path issues:
1. cache-dependency-path needs full path from repo root
2. cypress-io/github-action working-directory needs full path
3. Upload artifacts paths need full path from repo root

All paths must be relative to the repository root, not the global
working directory setting.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: davdhacs

.github/workflows/PR.yaml

@@ -214,7 +214,7 @@ jobs:
         with:
           node-version: '20'
           cache: 'npm'
-          cache-dependency-path: ui/package-lock.json
+          cache-dependency-path: go/src/github.com/stackrox/infra/ui/package-lock.json
 
       - name: Install UI dependencies
         run: |
@@ -244,7 +244,7 @@ jobs:
       - name: Run UI E2E tests
         uses: cypress-io/github-action@v6
         with:
-          working-directory: ui
+          working-directory: go/src/github.com/stackrox/infra/ui
           start: npm run start
           wait-on: 'http://localhost:3001'
           wait-on-timeout: 60
@@ -262,8 +262,8 @@ jobs:
         with:
           name: cypress-artifacts-pr-cluster-${{ github.event.pull_request.number }}
           path: |
-            ui/cypress/videos
-            ui/cypress/screenshots
+            go/src/github.com/stackrox/infra/ui/cypress/videos
+            go/src/github.com/stackrox/infra/ui/cypress/screenshots
           retention-days: 7
 
       - name: Cleanup port-forward