add a container build environment

Dockerfile provisions CUDA 12.8, ZED SDK 5.2, ONNX Runtime and Rust on
Ubuntu 24.04, the newest release Stereolabs ships a ZED SDK for, so the
node can be compiled and the build verified without installing the SDK
stack on the host.

The compile needs --gpus all: libsl_zed.so links against the CUDA driver
API, NVDEC and NVENC, which ship with the display driver rather than the
CUDA toolkit and so exist in no image. The container runtime mounts them
from the host, and only includes NVDEC/NVENC when the video capability
is requested.

Runs as the invoking user so build/ and bin/ are not left root-owned,
which needs the toolchain outside /root and the ZED SDK directory
readable to an arbitrary uid.

.dockerignore

@@ -0,0 +1,5 @@
+.git/
+build/
+bin/
+tmp/
+models/