fix: add v4l-utils to server Dockerfile for cec-ctl

CecController uses cec-ctl (from v4l-utils), not cec-client (from cec-utils).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Alex

docker/Dockerfile.server

@@ -56,6 +56,7 @@ RUN \
         python-is-python3 \
         sudo \
         sqlite3 \
+        v4l-utils \
         zlib1g-dev
 
 # We need this to ensure that the wheels can be built.