fix: use venv python for uvicorn and add node version check

start_server.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 # --- CONFIGURATION (Default values, will be overridden by network_configinventory.env) ---
 BACKEND_PORT=8000
@@ -59,10 +59,18 @@ EOF
 
 echo "🔥 Starting Backend on port $BACKEND_PORT..."
 echo "   CORS origins: $ALLOWED_ORIGINS"
-python3 -m uvicorn backend.main:app --host 0.0.0.0 --port $BACKEND_PORT --reload &
+.venv/bin/python -m uvicorn backend.main:app --host 0.0.0.0 --port $BACKEND_PORT --reload &
 
 # 5. Start Frontend (Next.js)
 echo "💻 Starting Frontend on port $FRONTEND_PORT..."
+
+# Check Node.js version
+NODE_VERSION=$(node -v | cut -d'v' -f2 | cut -d'.' -f1)
+if [ "$NODE_VERSION" -lt 20 ]; then
+    echo "⚠️  WARNING: Node.js v20+ required, but found $(node -v)"
+    echo "   Please upgrade Node.js: https://nodejs.org/"
+fi
+
 cd frontend
 echo "📦 Installing frontend dependencies..."
 npm install