Add python3 to final image for devtools-frontend HTTP server

📝 Changes:
- Added python3 and python-is-python3 to runtime dependencies in Dockerfile.cloudrun
- Required for supervisor devtools-frontend service which runs: python3 -m http.server 8001
- This will allow the custom DevTools frontend to be served properly

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: olesho

Dockerfile.cloudrun

@@ -206,7 +206,7 @@ ENV USERNAME=kernel
 RUN set -eux; \
     apt-get update; \
     apt-get install -y --no-install-recommends \
-    wget ca-certificates python2 supervisor xclip xdotool \
+    wget ca-certificates python2 python3 python-is-python3 supervisor xclip xdotool \
     pulseaudio dbus-x11 xserver-xorg-video-dummy \
     libcairo2 libxcb1 libxrandr2 libxv1 libopus0 libvpx7 \
     gstreamer1.0-plugins-base gstreamer1.0-plugins-good \