Fix e2e: show headless Chromium errors, add missing deps for screenshot

The headless screenshot silently failed (2>/dev/null hid the error).
Now show stderr, use --headless=new, --disable-dev-shm-usage, and
add missing shared libraries (libnss3, libgbm1, etc.) needed for
Chromium headless in the container environment.

Author: guysoft

testing/Dockerfile

@@ -3,7 +3,9 @@ FROM ptrsr/pi-ci:latest
 ENV LIBGUESTFS_BACKEND=direct
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
-    sshpass openssh-client curl socat imagemagick chromium \
+    sshpass openssh-client curl socat imagemagick \
+    chromium libnss3 libatk1.0-0 libatk-bridge2.0-0 libgbm1 \
+    libasound2t64 libxcomposite1 libxdamage1 libxrandr2 fonts-liberation \
     && rm -rf /var/lib/apt/lists/*
 
 # Shared framework from CustomPiOS (copied into build context by CI)

testing/hooks/screenshot.sh

@@ -30,19 +30,32 @@ if [ "$WIZARD_READY" -eq 0 ]; then
 fi
 
 HTTP_PORT="${QEMU_HTTP_PORT:-8080}"
-for BROWSER in chromium chromium-browser google-chrome; do
-    if command -v "$BROWSER" &>/dev/null; then
-        echo "  Using $BROWSER for headless screenshot..."
-        "$BROWSER" --headless --disable-gpu --no-sandbox \
+
+echo "  Checking forwarded port accessibility..."
+curl -s -o /dev/null -w "  Port $HTTP_PORT -> HTTP %{http_code}\n" "http://localhost:${HTTP_PORT}" || echo "  Port $HTTP_PORT not reachable"
+
+for BROWSER in chromium chromium-browser; do
+    BROWSER_PATH=$(command -v "$BROWSER" 2>/dev/null || true)
+    if [ -n "$BROWSER_PATH" ]; then
+        echo "  Taking headless screenshot with $BROWSER_PATH ..."
+        "$BROWSER_PATH" \
+            --headless=new \
+            --no-sandbox \
+            --disable-gpu \
+            --disable-software-rasterizer \
+            --disable-dev-shm-usage \
             --virtual-time-budget=15000 \
             --screenshot="$ARTIFACTS_DIR/screenshot.png" \
             --window-size=1280,720 \
-            "http://localhost:${HTTP_PORT}" 2>/dev/null || true
+            "http://localhost:${HTTP_PORT}" 2>&1 | tail -5 || true
         if [ -f "$ARTIFACTS_DIR/screenshot.png" ]; then
-            echo "  Browser screenshot saved"
+            echo "  Screenshot saved to $ARTIFACTS_DIR/screenshot.png"
+            ls -la "$ARTIFACTS_DIR/screenshot.png"
             exit 0
+        else
+            echo "  Screenshot file was NOT created by $BROWSER"
         fi
     fi
 done
 
-echo "  No headless browser available in container (HTML artifact saved instead)"
+echo "  No screenshot produced (headless browser may have failed)"