added pre-development files

.devcontainer/Dockerfile.backend

@@ -0,0 +1,28 @@
+FROM python:3.14-slim
+
+ARG USERNAME=vscode
+WORKDIR /workspace
+
+# Install system dependencies
+RUN apt-get update && apt-get install -y \
+    postgresql-client \
+    iputils-ping \
+    nmap \
+    build-essential \
+    libpq-dev \
+    git \
+    curl \
+    && rm -rf /var/lib/apt/lists/*
+
+RUN curl -fsSL https://deb.nodesource.com/setup_18.x | bash - && \
+    apt-get install -y nodejs
+
+# Install Python dependencies
+COPY ../requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+# Expose port
+EXPOSE 8000
+
+# Default command (overridden by devcontainer.json)
+CMD ["sleep", "infinity"]