feat: show node connection status and traffic stats in admin panel

Enable sing-box Clash/V2Ray APIs for per-user metrics, persist cumulative
traffic in SQLite, and refresh the dashboard every five seconds.

Co-authored-by: Cursor <cursoragent@cursor.com>

scripts/install.sh

@@ -61,6 +61,16 @@ fi
 : "${REALITY_SHORT_ID:?}"
 : "${PANEL_PASSWORD:?}"
 
+if [[ -z "${CLASH_API_SECRET:-}" ]]; then
+  CLASH_API_SECRET="$(openssl rand -hex 16)"
+  if grep -q "^CLASH_API_SECRET=" "$ENV_FILE" 2>/dev/null; then
+    sed -i "s|^CLASH_API_SECRET=.*|CLASH_API_SECRET=${CLASH_API_SECRET}|" "$ENV_FILE"
+  else
+    echo "CLASH_API_SECRET=${CLASH_API_SECRET}" >> "$ENV_FILE"
+  fi
+  source "$ENV_FILE"
+fi
+
 normalize_panel_path() {
   local p="${1:-}"
   p="${p#/}"