ci: continue-on-error for upload-artifact steps (Gitea GHES unsupported)

upload-artifact@v4 and download-artifact@v4 are not supported on
Gitea Actions (GHES), so coverage + Playwright report uploads fail
the whole job even when every test passes. Mark those three upload
steps as continue-on-error so test success is not gated on artifact
persistence — the artifacts are still useful locally via act / the
job logs, just not retained server-side.

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

.github/workflows/ci.yml

@@ -213,6 +213,7 @@ jobs:
 
       - name: Upload coverage reports
         uses: actions/upload-artifact@v4
+        continue-on-error: true # upload-artifact@v4 unsupported on Gitea (GHES) runner
         if: ${{ !cancelled() }}
         with:
           name: coverage-reports
@@ -353,6 +354,7 @@ jobs:
 
       - name: Upload Playwright report
         uses: actions/upload-artifact@v4
+        continue-on-error: true # upload-artifact@v4 unsupported on Gitea (GHES) runner
         if: ${{ !cancelled() }}
         with:
           name: playwright-report
@@ -432,6 +434,7 @@ jobs:
 
       - name: Upload Playwright report
         if: failure()
+        continue-on-error: true # upload-artifact@v4 unsupported on Gitea (GHES) runner
         uses: actions/upload-artifact@v4
         with:
           name: playwright-smoke-report