feat(fls): DNS records from /dns/hosts, as Java's server answers them

Java's DNS server reads its records from the text file /dns/hosts on every
query. dnsHosts.ts ports that reading (DNSServer.leseRecordListe,
ResourceRecord, Dateisystem.holeDatei) and keeps in the model the records
Java answers: type exactly A, MX or NS, and a name Java accepted. The file
stays in the file system as it is.

Both oracles read 76 hand-picked hosts files (dns-hosts.cases.txt): the
Java oracle through DNSServer.holeResourceRecords (DnsHostsCases), the
Swift oracle through TopologyDNSHostsFileCodec (--dns-hosts). The Java view
matches Java on every case; the model matches Swift except for 33 named
cases in twelve reasons: Java splits at single spaces and LF only, has no
comments or "IN", turns a TTL that is no int into 3600, keeps duplicates,
and empties names with a leading digit. The Swift dump now carries each
server's records; the corpus comparison covers them on 16 files.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tools/swift-oracle/README.md

@@ -38,6 +38,11 @@ Sortierung, Base64 — und die ganzen Mengen `whitespacesAndNewlines` und
 unter Linux; ihre Steuerzeichen-Tabelle hat in Ebene 14 einen Fehler, den
 der Port nicht übernimmt.
 
+`--dns-hosts` liest dieselben `/dns/hosts`-Fälle wie das Java-Orakel
+(`packages/fls/test/dns-hosts.cases.txt`) mit Swifts
+`TopologyDNSHostsFileCodec`; unter `state` stehen die DNS-Einträge jedes
+Servers (`dnsServer.records`).
+
 ## Wie es gebaut wird
 
 `fetch-upstream.sh` holt `filius-ipad` am festen Stand `3b5ded0` und kopiert