acb2096406
Two CI-only changes ported from pi-devbox (no runtime/image impact), adapted to opencode-devbox's split-base 2-variant pipeline. Rides the next release. C — eliminate the sh-vs-bash footgun class: - Add `defaults: run: shell: bash` workflow-wide to docker-publish-split.yml and validate.yml. Gitea's default step shell is sh/dash, so bash-only syntax in a step that omits `shell: bash` fails silently. All pre-existing steps are POSIX, so bash runs them unchanged (no behavioural change). - New .gitea/workflows/lint.yml (push/PR/dispatch): a Gitea-accurate shell guard (scripts/check-workflow-shell.sh) + pinned actionlint + shellcheck. The guard closes the actionlint blind spot: actionlint models GitHub (default shell bash) so it does NOT flag bash syntax in a shell-less step. Guard scans ALL .gitea/workflows/*.yml (hence the validate.yml default too). Ported from pi-devbox 26384fe/d1db595. B — promote-base-latest re-points base-latest by digest, not need_build: The gate keyed off need_build=='true', assuming need_build==false meant base-latest was current. A dry-run dispatch that pre-builds base-<hash> falsifies that, leaving base-latest one base behind. Gate now runs on every tag release / promote dispatch; the no-op optimization moved into the step as a crane digest compare (re-tags only when base-latest != released base-<hash>). Ported from pi-devbox b7197e8. Validated locally: all 3 workflows YAML-parse; shell guard passes real workflows and correctly fails a synthetic omit-shell+pipefail workflow; actionlint (pinned 1.7.7) passes with explicit .gitea/workflows/*.yml glob.