fix: improve venv creation with error checking and proper validation

start_server.sh

@@ -24,11 +24,12 @@ pkill -f "next-server" || true
 pkill -f "local-ssl-proxy" || true
 
 # 2. Setup/Activate Virtual Environment
-if [ ! -d ".venv" ]; then
+if [ ! -f ".venv/bin/activate" ]; then
     echo "🌑 Creating virtual environment (.venv)..."
-    python3 -m venv .venv
+    rm -rf .venv
+    python3 -m venv .venv || { echo "❌ Failed to create venv"; exit 1; }
 fi
-source .venv/bin/activate
+source .venv/bin/activate || { echo "❌ Failed to activate venv"; exit 1; }
 
 # 3. Check and Install Backend Dependencies
 echo "📦 Updating Python dependencies..."