- geoip.DefaultCacheDir() → ~/.cache/maxmind (os.UserCacheDir based)
- check-ip defaults data dir to ~/.cache/bitwire-it; -data-dir flag overrides;
positional data-dir arg removed (IP is now the only required arg)
- geoip conf: DatabaseDirectory defaults to geoip.DefaultCacheDir() when blank
- httpcache integration tests now cover both inbound files (single_ips + networks)
httpcache: write <path>.meta JSON sidecar after each successful download;
load it on first Fetch so conditional GETs work after process restarts.
Tests verify: download, sidecar written, same-cacher 304, fresh-cacher 304
(the last being the key case — no in-memory state, sidecar drives ETag).
MaxMind integration test reads GeoIP.conf, downloads City+ASN, verifies
fresh-cacher conditional GET skips re-download via sidecar ETag.
