feat: direct client creation + auto-detect AWG container

Add "Новый клиент" (direct) flow alongside cascade:
- server.js: POST /api/clients/create — Endpoint = this server's
  public IP:ListenPort (CLIENT_CONFIG_ENDPOINT or request host),
  reuses the same key/peer/conf pipeline as create-cascade.
- public/index.html: "Новый клиент" panel with #direct-form
  (name + optional tunnel IP).
- public/app.js: downloadDirectConf() handler + form binding.

install.sh hardening so fresh installs work out of the box:
- Auto-detect a single amnezia-awg* container (e.g. amnezia-awg2,
  Amnezia AWG 2.0 default) -> AWG_CONTAINER, instead of the fixed
  "amnezia-awg" default that mismatched and blocked client ops.
- Auto-default CLIENT_CONFIG_ENDPOINT to the host primary IP so
  direct .conf exports get a correct Endpoint without manual env.

Fixes "cannot create users" on servers whose WG container is
named amnezia-awg2.

scripts/install.sh

@@ -145,6 +145,17 @@ if [[ -z "${AWG_PROFILES:-}" ]] && [[ -f "${AWG_PROFILE_SNAPSHOT}" ]]; then
   fi
 fi
 
+# Авто-определение единственного контейнера amnezia-awg* (например amnezia-awg2 —
+# дефолт Amnezia для AWG 2.0), если AWG_CONTAINER и AWG_PROFILES не заданы вручную.
+if [[ -z "${AWG_CONTAINER:-}" ]] && [[ -z "${AWG_PROFILES:-}" ]]; then
+  __awg_names="$(docker ps --format '{{.Names}}' 2>/dev/null | grep -E '^amnezia-awg' || true)"
+  __awg_names_count="$(printf '%s\n' "${__awg_names}" | grep -c . || true)"
+  if [[ "${__awg_names_count}" == "1" ]]; then
+    AWG_CONTAINER="$(printf '%s\n' "${__awg_names}" | head -n1)"
+    echo "→ AWG_CONTAINER авто-определён: ${AWG_CONTAINER}"
+  fi
+fi
+
 if [[ -z "${AWG_PROFILES:-}" ]]; then
   __awg_multi_count="$(
     docker ps --format '{{.Names}}' 2>/dev/null | awk '/^amnezia-awg/ { c++ } END { print c + 0 }' | tr -d '[:space:]'
@@ -213,6 +224,14 @@ for __warp_var in WARP_DIR WARP_CONF_PATH WARP_CLIENTS_LIST AMNEZIA_START_SCRIPT
   fi
 done
 
+if [[ -z "${CLIENT_CONFIG_ENDPOINT:-}" ]]; then
+  __pub_ip="$(hostname -I 2>/dev/null | awk '{print $1}' || true)"
+  if [[ -n "${__pub_ip}" ]]; then
+    CLIENT_CONFIG_ENDPOINT="${__pub_ip}"
+    echo "→ CLIENT_CONFIG_ENDPOINT авто: ${CLIENT_CONFIG_ENDPOINT} (можно переопределить переменной окружения)"
+  fi
+fi
+
 for __export_var in CLIENT_CONFIG_ENDPOINT CLIENT_EXPORT_DNS1 CLIENT_EXPORT_DNS2 EXPORT_CONFIG_SECRET; do
   if [[ -n "${!__export_var:-}" ]]; then
     RUN_ENV+=( -e "${__export_var}=${!__export_var}" )