fix(cistech-tunnel): add software rendering support for Qt WebEngine

- Add QT_QUICK_BACKEND=software, LIBGL_ALWAYS_SOFTWARE=1
- Add mesa-utils, libgl1-mesa-dri for llvmpipe software renderer
- Add missing xcb libraries (libxcb-render0, libxcb-shm0, etc.)
- Use --use-gl=swiftshader in chromium flags

apps/cistech-tunnel/shared/xstartup

@@ -14,12 +14,18 @@ export XDG_RUNTIME_DIR=/tmp/runtime-root
 mkdir -p $XDG_RUNTIME_DIR
 chmod 700 $XDG_RUNTIME_DIR
 
+# Force software rendering (no GPU/OpenGL)
+export QT_QUICK_BACKEND=software
+export LIBGL_ALWAYS_SOFTWARE=1
+export GALLIUM_DRIVER=llvmpipe
+export MESA_GL_VERSION_OVERRIDE=3.3
+
 # GPU/WebKit workarounds for Cisco UI
 export GDK_BACKEND=x11
 export WEBKIT_DISABLE_DMABUF_RENDERER=1
 
 # Qt/Chromium flags for running as root (no sandbox)
-export QTWEBENGINE_CHROMIUM_FLAGS="--no-sandbox --disable-gpu"
+export QTWEBENGINE_CHROMIUM_FLAGS="--no-sandbox --disable-gpu --use-gl=swiftshader"
 export QTWEBENGINE_DISABLE_SANDBOX=1
 
 # Start dbus session