- check_versions.py: restore correct file (import re was placed before
shebang causing E402 for all following imports; missing 'client' in
kubernetes import causing F821 at line 236)
- request_upgrades.py: remove unused 're' import and unused 'client'
from kubernetes import (only 'config' is needed here)
- web.py: remove unused 'os' import
- Add request_upgrades.py and trigger-upgrade.sh
- Add upgrade-cronjob.yaml and manual-trigger.yaml (WorkflowTemplate)
- Fix git auth: use GITEA_USERNAME env var instead of hardcoded x-token
(Gitea requires username:token format, not x-token:token)