CI: add sequential tag for NoteEquipTitleTest; woodpecker runs it w.o --parallel

Parallel geckodriver startup race causes a spurious permissions error when
NoteEquipTitleTest is the first FT dispatched. @tag("sequential") moves it
into test-two-browser-FTs (sequential stage) as a reusable escape hatch.

Code architected by Disco DeDisco <discodedisco@outlook.com>
Git commit message Co-Authored-By:
Claude Sonnet 4.6 <noreply@anthropic.com>

.woodpecker/main.yaml

@@ -42,6 +42,7 @@ steps:
       - cd ./src
       - python manage.py collectstatic --noinput
       - python manage.py test functional_tests --tag=two-browser
+      - python manage.py test functional_tests --tag=sequential
       - python manage.py test functional_tests --tag=channels
     when:
       - event: push