Add self-hosted C++ workflow

[scal444]

No description provided.

[greptile-apps]

Greptile Summary

This PR introduces a self-hosted C++ CI workflow that builds and tests the project inside a pinned nvcr.io/nvidia/cuda:12.6.3-devel-ubuntu22.04 container, along with a setup_dependencies.sh script that installs Miniforge and the required conda packages. The SHA-256 integrity check for the Miniforge installer has been added, resolving the prior security concern.

Confidence Score: 5/5

Safe to merge; all remaining findings are P2 style suggestions that do not block correct operation.

The previously flagged security concern (missing Miniforge checksum) is now resolved, the container image is pinned to a specific version, and the only new finding is an inconsistent -u flag in set options — a non-blocking style issue.

No files require special attention.

Important Files Changed

Filename	Overview
.github/workflows/cpp-build-test.yml	New self-hosted C++ CI workflow using a pinned CUDA 12.6.3 container; minor inconsistency in set flags (-u missing in Configure/Build/Test steps) and the CC/CXX compiler-selection issue discussed in prior threads remains unresolved.
admin/ci/setup_dependencies.sh	Installs Miniforge and conda packages; SHA-256 integrity check for the installer has been added (resolving the prior security finding); compiler CC/CXX exports have been removed.

_{Reviews (12): Last reviewed commit: "Fix hash issue" | Re-trigger Greptile}