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

scripts/install_windows.ps1

@@ -10,10 +10,6 @@
 $ErrorActionPreference = "Stop"
 
 $ZED_INSTALL_DIR = "C:\Program Files (x86)\ZED SDK"
-$ORT_VERSION     = "1.24.4"
-$ORT_NAME        = "onnxruntime-win-x64-gpu_cuda13-$ORT_VERSION"
-$ORT_URL         = "https://github.com/microsoft/onnxruntime/releases/download/v$ORT_VERSION/$ORT_NAME.zip"
-$ORT_DEST        = "C:\onnxruntime"
 
 # --- ZED SDK ---
 if (Test-Path $ZED_INSTALL_DIR) {
@@ -25,23 +21,5 @@ if (Test-Path $ZED_INSTALL_DIR) {
     Write-Host ""
 }
 
-# --- ONNX Runtime ---
-if (Test-Path "$ORT_DEST\lib\onnxruntime.dll") {
-    Write-Host ">>> ONNX Runtime already installed at '$ORT_DEST' — skipping."
-} else {
-    Write-Host ">>> Downloading ONNX Runtime $ORT_VERSION GPU (CUDA 13)..."
-    $tmp = "$env:TEMP\$ORT_NAME.zip"
-    Invoke-WebRequest -Uri $ORT_URL -OutFile $tmp
-
-    Write-Host ">>> Extracting to $ORT_DEST..."
-    Expand-Archive -Path $tmp -DestinationPath $env:TEMP -Force
-    if (Test-Path $ORT_DEST) { Remove-Item $ORT_DEST -Recurse -Force }
-    Move-Item "$env:TEMP\$ORT_NAME" $ORT_DEST
-    Remove-Item $tmp
-
-    Write-Host ">>> ONNX Runtime installed to $ORT_DEST"
-    Write-Host "    Pass it to CMake: cmake .. -DCMAKE_PREFIX_PATH=C:\onnxruntime"
-}
-
 Write-Host ""
 Write-Host ">>> Done."