config/settings_test.go was removed from the whole history because its fixtures
used a real QQ number and group ID. This adds the file back as a new commit
whose fixtures are placeholder IDs, so the deep-merge, null-delete, array-replace
and settings-type validation coverage is kept without the identifiers.
The file has no history before this commit by design: the old blobs are gone
from every ref, and the working copy has been rebuilt from the redacted
version.
Co-Authored-By: Claude Code <noreply@anthropic.com>
