fix(sandbox): install fonts-dejavu-core in the runtime image (#16032)

The capture card renderer in scripts/verify-capture.mjs requests DejaVu Sans Mono, but the runtime image installs no font packages at all.


Patrol-Run: qwen-issue-patrol/jmvx4obxsrz

Co-authored-by: yiliang114 <[email protected]>
Co-authored-by: Qwen-Coder <[email protected]>
Co-authored-by: Shaojin Wen <[email protected]>

Dockerfile

@@ -62,6 +62,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   lsof \
   socat \
   ca-certificates \
+  fonts-dejavu-core \
   && apt-get clean \
   && rm -rf /var/lib/apt/lists/*