feat: add gh CLI to reviewer container image

container/Dockerfile

@@ -12,6 +12,11 @@ RUN apt-get update --fix-missing && apt-get install -y --no-install-recommends \
     fonts-noto-color-emoji \
     curl \
     git \
+    && curl -fsSL https://cli.github.com/packages/githubcli-archive-keyring.gpg \
+       | dd of=/usr/share/keyrings/githubcli-archive-keyring.gpg \
+    && echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/githubcli-archive-keyring.gpg] https://cli.github.com/packages stable main" \
+       > /etc/apt/sources.list.d/github-cli.list \
+    && apt-get update && apt-get install -y --no-install-recommends gh \
     && rm -rf /var/lib/apt/lists/*
 
 # Chromium paths for Playwright/agent-browser