bug: ts-admin does not support newly added retention offers

[the-leonat]

Provide environment information

System:
    OS: macOS 26.2
    CPU: (10) arm64 Apple M2 Pro
    Memory: 119.55 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 24.6.0 - /opt/homebrew/bin/node
    Yarn: 1.22.22 - /Users/leonard/.bun/bin/yarn
    npm: 11.5.1 - /opt/homebrew/bin/npm
    bun: 1.3.6 - /Users/leonard/Documents/3_WORK/2025/surplus/surplus-agent.nosync/node_modules/.bin/bun
    Deno: 2.3.3 - /opt/homebrew/bin/deno
  Browsers:
    Brave Browser: 114.1.52.130
    Chrome: 146.0.7680.81
    Firefox: 147.0.3
    Safari: 26.2

Describe the bug

const result = await ghost.offers.browse({ filter: "status:active" }).fetch()

call to offer endpoint fails on zod typecheck with newly added retention offers are added to ghost backend. retention offers can contain a tier = null, which is not supported within the zod return type.

further reading: https://ghost.org/changelog/retention-offers/

Target Ghost Blog version

v6.22.x

To reproduce

const result = await ghost.offers.browse({ filter: "status:active" }).fetch()

Additional information

No response

👨‍👧‍👦 Contributing

• 🙋‍♂️ Yes, I'd be down to file a PR fixing this bug!