48 kHz only: drop 96 kHz from the AES67 output

All sources (player, test signals) are 48 kHz; at 96 kHz Spotify and HLS
played at the wrong speed. Validation, the page and the docs allow 48000
only, and a 96000 stored before is reset to 48000 at boot (stored values
aren't re-validated, and the SDP would still have said 96 kHz).

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

docs/aes67-core-base.md

@@ -19,7 +19,7 @@ Reference devices for UI and defaults: Riedel Bolero (PTP status), Riedel Direct
 
 ## Config schema (core groups)
 - ptp: {mode: multicast|hybrid, role: slave|auto|master, domain, priority1, priority2, log_sync, log_announce, announce_timeout, log_delay_req, dscp, hw_ts}
-- aes67: {name, enabled, discovery: manual|sap, mcast, port, ttl, dscp, channels, mono_sum, encoding: L16|L24, rate, ptime, pt, ssrc, clk_offset, session_id, session_ver}
+- aes67: {name, enabled, discovery: manual|sap, mcast, port, ttl, dscp, channels, mono_sum, encoding: L16|L24, rate: 48000 only (all sources are 48 kHz), ptime, pt, ssrc, clk_offset, session_id, session_ver}
 - net: {hostname, vlan, web_on: both|inet|aes67, dhcp, ip, mask, gw, dns}   (AES67 / untagged interface)
 - inet: {vlan_id, pcp, dhcp, ip, mask, gw, dns}                            (internet / tagged, only if net.vlan)
 - log: {syslog, host, port, level: error|warn|info|debug, facility, format: rfc5424|rfc3164}