feat: add noVNC headed mode for interactive browser sessions

- Dockerfile with Xvfb + x11vnc + noVNC for browser-in-a-URL
- search.py auto-detects DISPLAY env to run headed vs headless
- pause_for_human() function for CAPTCHA/login handoff
- Facebook Marketplace search (headed mode only, needs login)
- Updated README with both modes

Dockerfile

@@ -0,0 +1,29 @@
+FROM python:3.13-slim
+
+# Install display and VNC deps
+RUN apt-get update -qq && apt-get install -y -qq --no-install-recommends \
+    xvfb x11vnc websockify novnc \
+    libnss3 libatk1.0-0 libatk-bridge2.0-0 libcups2 libdrm2 \
+    libxkbcommon0 libxcomposite1 libxdamage1 libxrandr2 libgbm1 \
+    libpango-1.0-0 libcairo2 libasound2 libxshmfence1 libgtk-3-0 \
+    fonts-liberation && \
+    rm -rf /var/lib/apt/lists/*
+
+# Install Python deps
+COPY pyproject.toml uv.lock /app/
+WORKDIR /app
+RUN pip install uv && uv sync --frozen
+
+# Install Playwright Chromium
+RUN uv run playwright install chromium
+
+# Copy source
+COPY . /app/
+
+# Entrypoint script
+COPY entrypoint.sh /entrypoint.sh
+RUN chmod +x /entrypoint.sh
+
+EXPOSE 6080
+
+ENTRYPOINT ["/entrypoint.sh"]