feat: suppress sac-fail.count on shutdown (2.3.2-SAC)

Phase 4.2: SAC_SUPPRESS_FAIL_COUNT during lifecycle shutdown so restart during SAC deploy does not trip Telegram fallback. Add docs/sac-ingest.ru.md for SAC_TIMEOUT_SEC guidance, smoke test, and release manifest.

contrib/test-sac-fail-count.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+# Smoke-test sac-fail.count suppress on shutdown flag. Run from repo root.
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+tmpdir="$(mktemp -d)"
+trap 'rm -rf "$tmpdir"' EXIT
+
+write_log() { :; }
+ssh_monitor_secure_file() { :; }
+ssh_monitor_secure_dir() { mkdir -p "$1"; }
+
+# shellcheck source=sac-client.sh
+source "$ROOT/sac-client.sh"
+
+export SAC_FAIL_COUNT_FILE="${tmpdir}/sac-fail.count"
+
+sac_write_fail_count 0
+sac_increment_fail_count
+[ "$(sac_read_fail_count)" = "1" ] || {
+	echo "FAIL: expected count 1 after increment" >&2
+	exit 1
+}
+
+SAC_SUPPRESS_FAIL_COUNT=1
+sac_increment_fail_count || true
+[ "$(sac_read_fail_count)" = "1" ] || {
+	echo "FAIL: count changed under SAC_SUPPRESS_FAIL_COUNT" >&2
+	exit 1
+}
+
+echo "OK sac-fail.count suppress"