- ha.c: add raft_cb_trace callback wired to s_real_cbs.on_trace; emits
RAFT[pN] term=T event=E at DEBUG3 level, visible with -vvv flag.
- ha.c: repl_ack_decode_and_dispatch now silently drops OPCode_nop and
OPCode_reply instead of WARNING — heartbeat NOP replies from standbys
arrive on promoted endpoints and are expected.
- deploy-ha.sh: fix --vcpu -> --vcpus; add \$VERBOSE passthrough so
start.sh respects VERBOSE=-vvv from the environment.
