Whether to merge into a writable settings.json at activation instead of linking it from the Nix store.
A store-linked file prevents the CLI from saving settings normally. Versions that replace the file when saving a model or theme replace the link, causing a collision on the next activation.
When enabled, declared values take precedence over existing values, keys later removed from stay in the file, and comments and formatting are not preserved. Turning the option off links the file again. A merged file is replaced automatically only when it is byte-identical to the declared settings. Other files are left to the normal collision and backup handling. If the remaining settings are empty, the file is left unmanaged.