Froxlor: BIND Zone File Injection via TXT Record Content

Froxlor is open source server administration software. Prior to version 2.3.7, the `DomainZones.add` API endpoint does not sanitize newline characters in TXT record content. An authenticated customer with DNS editing enabled can inject newlines into TXT record values, which break out of the record line in the generated BIND zone file. This enables injection of arbitrary BIND directives (`$INCLUDE`, `$GENERATE`) and arbitrary DNS records (A, MX, CNAME) into the zone file written to disk by the DNS rebuild cron. This is an incomplete fix for CVE-2026-30932 (GHSA-x6w6-2xwp-3jh6), which patched the same newline injection for LOC, RP, SSHFP, and TLSA record types but did not patch TXT records. Version 2.3.7 contains an updated patch.