Set up a Polaroid photo wall for the internal test finale of DeepSeek Harness with dsh-group-photo

`dsh-group-photo` is a fun plugin for DeepSeek Harness maintained by SenmuuuuW: a polaroid group photo wall prepared for the final closing of the DSH internal test. Members log in via zero-permission GitHub OAuth, and only internal test identities on the frozen whitelist can appear in the photo and leave messages. The main body is a dependency-free Node site, and the repository also includes a DSH Skill package. The directory installation command is `dsh plugin add github:SenmuuuuW/dsh-group-photo`, and it can be started locally on port 8808 with `npm start`. The license is MIT.