Caches of outside APIs live in /var/cache/sww (closes #314)

The answers of GeoJS, the lists fetched by URL, the DNS blocklists and
AbuseIPDB each go in a cache file in SWW_CACHE_DIR (default
/var/cache/sww): lookups.json, lists.json, dnsbl.json and
abuseipdb-scores.json. reputation.json is gone. The AbuseIPDB checks
spent today are a count, not a cache, and stay in SWW_STATE_DIR as
abuseipdb-checks.json.

A cache file never stops the start: one that does not parse is set
aside as an edit is, one that cannot be read is written over, and its
cache starts empty. An unwritable SWW_CACHE_DIR stops the start, as an
unwritable SWW_STATE_DIR does. The run script makes the cache directory
and gives it to sww.

Model: opus-5-5

internal/sww/sww.go

@@ -244,6 +244,7 @@ func loadStateFiles(
 ) (*state.Files, error) {
 	return state.Load(state.Params{
 		Dir:             cfg.StateDir,
+		CacheDir:        cfg.CacheDir,
 		WriteDelay:      cfg.StateWriteDelay,
 		CounterInterval: cfg.StateCounterInterval,
 		Ledger:          server.Ledger,