feat(cities-skymine): add server config access command

[marzipan99]

Summary

• move the personal settings GUI from /csm config / /.cf to /csm settings / /.settings
• add /csm config / /.config for editing CitiesSkyMine config.yml access settings
• add admin-only protection for the config editing command, plus tab completion and help
• refresh the CitiesSkyMine user guide markdown with current commands and config access examples

Validation

• /nix/var/nix/profiles/default/bin/nix fmt
• /nix/var/nix/profiles/default/bin/nix develop --command gradle :plugins:CitiesSkyMine:build
• git diff --check

Notes

• The new config command currently edits only access-related settings.
• The config editor is hard-gated to OP, citiesskymine.config, citiesskymine.admin, or citiesskymine.role.admin so old access.commands.config values cannot accidentally grant server config editing.