Self-hosted: add config for turn off signup feature about affine HOT 2 OPEN

we have refactoring related components in the last two major versions, and the corresponding env var are outdated.

please go to our docs to view the latest available env vars: https://docs.affine.pro/docs/self-host-affine/run-affine-with-custom-options

specifically, in the latest version, as long as the OAUTH_* env are not defined, the oauth feature will be turned off, but there is currently no config item that can turn off the registration feature.

i have recorded the config item of turn off the registration feature in the development schedule, once there are relevant updates, i will associate it with this issue.

from affine.

Issue Status: 🔍 Under Investigation

🔍 Under Investigation

We’ve triaged the issue, but now we need to investigate it more thoroughly. This may require processing additional information like logs or dumps.

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from affine.