chore: bump Ghost to 6.67.0; 6.65.0:0 → 6.67.0:0

[helix-a]

Summary

• Bump Ghost to 6.67.0 (ghost:6.67.0-alpine), shipping StartOS version 6.67.0:0.
• Tier: minor. Read the upstream release notes and changelog for the crossed range. The Admin improvements and fixes are available through Ghost itself; no new packaging action, task, or configuration is needed.
• Highlights: fixes post history for posts without revisions, empty mobiledoc imports, bulk-action selection, filters, scroll restoration, and Stripe subscription errors. Add release notes in all five locales.
• Verified the exact Docker Hub tag is active for amd64 and arm64. Ghost 6.66.0 had a failed npm publish; upstream recommends 6.67.0, whose image is available.
• start-sdk is already at the latest published version (2.0.9); there are no *-startos git dependencies to refresh. MySQL remains unchanged.
• The target StartOS version is absent from the production and beta registries. README and user instructions remain applicable: package configuration and workflows are unchanged.

Verification

• npm ci completed; npm run check passed.
• npm reported two high-severity dependency advisories during installation; their applicability has not been assessed in this cycle.
• No build, package installation, runtime testing, or review pass performed.

Testing

• Upgrade an existing Ghost site with posts, members, and uploaded media to 6.67.0:0; start it, confirm database/server health, log in at its primary URL, and verify existing content plus saving/publishing a post survive a restart.
• In Ghost Admin, open the history of a post without revisions, apply post filters and bulk selections, and navigate away from and back to scrolled posts/member lists; confirm these workflows remain usable without crashes or lost selections.

Merge with a merge commit — do not squash. next is long-lived: a merge commit leaves it a true ancestor of master, so it fast-forwards cleanly afterwards. A squash re-lands the same content under a new commit, so the branch is left carrying history master will never contain.