fix(fls): follow Java's formats, not Java's errors

Java stays the reference for the .fls format, but its errors are no longer
copied. The Java oracle still measures Java as it is; each deliberate
departure is named in the tests with its reason (JAVA_BUGS) and must really
depart. The corpus - what Java itself writes - still reads exactly as in
Java.

- /dns/hosts: a label may start with a digit, holds no backslash, and the
  last one is not all digits (RFC 1123, RFC 3696); A, MX and NS are read in
  any case (RFC 4343); a negative TTL is invalid, so 3600 (RFC 2181). Also
  for the e-mail server's domain.
- /mailserver/konten.txt: empty fields count (Java's StringTokenizer skips
  them and shifts the rest, so an empty password breaks the account); a
  short line alone is left out, with a warning (Java throws for the whole
  file); a message keeps an empty text or subject (Java's split loses it);
  a ";" in an unescaped subject stays in the message; CRLF lines.
- /konten.txt: the last complete line is the account, also with an empty
  address (Java takes the last line and loses the account); CRLF lines.
- Static DHCP assignments: a broken entry alone is left out (Java loses
  every entry after it).

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

tools/java-oracle/README.md

@@ -1,5 +1,12 @@
 # Java-Orakel
 
+Das Orakel misst Javas **echtes** Verhalten, Fehler eingeschlossen. Der
+TypeScript-Leser folgt Java, übernimmt aber keine Java-Fehler (Datenverlust,
+Absturz, eigene Ausgabe nicht wieder lesbar, Tippfehler, Verstoß gegen den
+Standard); jede solche Abweichung steht in den Tests namentlich mit Grund
+(`JAVA_BUGS`). Was Java selbst schreibt — der Korpus — wird exakt wie in
+Java gelesen.
+
 Java-Filius selbst liest den Korpus (`corpus/`) und schreibt, was es gefunden
 hat, nach `corpus/corpus.java.json`. **Java ist der Schiedsrichter für das
 Dateiformat** — der Swift-Leser verliert in 10 von 23 Dateien Geräte (Plan