remove detection from the node

dora-zed publishes camera data only. The two engines under src/engines/, the
objects output, the ZED_ENGINE/ZED_DETECTION_*/ZED_ONNX_* variables and the
ZED_PC_MODE=ROI crop are gone, along with the standalone engine test and the
model export script.

This drops the unconditional ONNX Runtime requirement from CMakeLists, the
Dockerfile and the install scripts, so the node now configures on a machine
with no ONNX Runtime — which is what blocked the Jetson build, since there is
no official ARM64 GPU binary.

zed_native is dropped rather than kept: it is bound to the live camera handle
and cannot run in a node that receives images over a dataflow. The removed
code remains reachable at tag v0.1.0.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Y7g2cBJ5e3r15ZbJ9WZn8c

Dockerfile

@@ -21,7 +21,6 @@
 FROM nvidia/cuda:12.8.1-devel-ubuntu24.04
 
 ARG ZED_VERSION=5.2
-ARG ORT_VERSION=1.24.4
 
 ENV DEBIAN_FRONTEND=noninteractive
 
@@ -51,24 +50,6 @@ RUN curl -fSL -o /tmp/ZED_SDK.run \
     && chmod -R a+rX /usr/local/zed \
     && rm -f /tmp/ZED_SDK.run
 
-# The tarball puts its CMake package files under lib/, but onnxruntimeTargets.cmake
-# resolves the library as <prefix>/lib64. Ubuntu is multiarch, so CMake does not
-# search lib64 for packages and ld.so does not search /usr/local/lib64 at all:
-# keep the libraries in lib64, move only the package files to lib/cmake, and add
-# lib64 to the linker path.
-RUN curl -fSL -o /tmp/ort.tgz \
-        "https://github.com/microsoft/onnxruntime/releases/download/v${ORT_VERSION}/onnxruntime-linux-x64-gpu-${ORT_VERSION}.tgz" \
-    && tar -xzf /tmp/ort.tgz -C /tmp \
-    && mkdir -p /usr/local/include/onnxruntime /usr/local/lib64 \
-    && cp -r /tmp/onnxruntime-linux-x64-gpu-${ORT_VERSION}/include/* /usr/local/include/onnxruntime/ \
-    && cp -r /tmp/onnxruntime-linux-x64-gpu-${ORT_VERSION}/lib/* /usr/local/lib64/ \
-    && mkdir -p /usr/local/lib/cmake \
-    && mv /usr/local/lib64/cmake/onnxruntime /usr/local/lib/cmake/ \
-    && rmdir /usr/local/lib64/cmake \
-    && echo /usr/local/lib64 > /etc/ld.so.conf.d/onnxruntime.conf \
-    && ldconfig \
-    && rm -rf /tmp/ort.tgz /tmp/onnxruntime-linux-x64-gpu-${ORT_VERSION}
-
 ENV NVIDIA_DRIVER_CAPABILITIES=compute,utility,video
 
 WORKDIR /src