* fix: raise UDP SO_RCVBUF on voice listeners (C-LOCAL)
Apply a 4 MB receive buffer on system and proxy UDP sockets to reduce
kernel RcvbufErrors under OBP load; size is configurable via GLOBAL.UDP_RCVBUF.
* fix: exclude byte-identical duplicates from HBP rate counter (A.2)
Check lastData before incrementing the ingress packet counter so compressed
duplicate bursts do not trigger legitimate RATE DROP on call start.
* fix: duplicate-safe TA embed phase and REPEAT VHEAD DMRA (B)
Ignore byte-identical B-E embed bursts so duplicate uplinks do not desync the
TA phase machine, and re-emit DMRA on every VHEAD on the REPEAT path.
* chore: document echo point-to-point and logged_in reconciliation (EN/ES)
Document multi-hotspot echo/service delivery via RX_PEER, the lst_seen
logged_in reconcile loop, and cross-links between user and dev guides.
Document 2.x routing model with a concrete TG 52090 example, operator-focused
performance gains (indexes, reporting, integrated proxy), and MkDocs Mermaid
support across server and monitor architecture pages.