improve useability

[ScSteffen]

kitrt_code PR Notes

Summary

This PR addresses the KiT-RT-side accessibility and usability gaps from kitrt_accessibility_usability_plan.md in the nested checkout at /home/8v5/projects/CharmKiT/kitrt_code.

Verified Gaps And Changes

• Documentation version drift existed: CMakeLists.txt reports 1.2.0, while doc/conf.py still reported v0.1. Updated Sphinx version and release to 1.2.0 and enabled version display.
• ReadTheDocs config was stale: .readthedocs.yml still used the legacy Python 3.7 selector. Updated it to the v2 build image/tool format with Python 3.11.
• The README lacked a first-run path and decision guide. Added a Start here section that explains kitrt_code versus CharmKiT, documents a ten-minute CPU smoke test, points sweep/SLURM users to CharmKiT, and points stuck users to troubleshooting.
• The docs lacked status/getting-started/troubleshooting pages. Added doc/status.rst, doc/getting_started.rst, and doc/troubleshooting.rst, and linked them from doc/index.rst.
• There was no canonical laptop smoke test. Added examples/configs/smoke_test.cfg, doc/tutorials/smoke_test.rst, and tools/check_smoke_output.py, plus an .gitignore exception so the new config appears in the PR.
• Installation docs did not route users through the smoke test. Updated doc/installation.rst with the smoke command and checker.
• Release docs only listed 0.1.0. Added a 1.2.0 section with the release artifact checklist and current commit-citation guidance until official releases are published.
• The container build helper was Singularity-only. Updated tools/singularity/build_container.sh to use KITRT_CONTAINER_RUNTIME, auto-detect Apptainer before Singularity, and keep the existing CPU/CUDA/ROCm modes.

Primary Files

• .gitignore
• .readthedocs.yml
• README.md
• doc/conf.py
• doc/index.rst
• doc/installation.rst
• doc/release.rst
• doc/status.rst
• doc/getting_started.rst
• doc/tutorials/smoke_test.rst
• doc/troubleshooting.rst
• examples/configs/smoke_test.cfg
• tools/check_smoke_output.py
• tools/singularity/build_container.sh

Verification

• python3 -m py_compile tools/check_smoke_output.py
• singularity exec tools/singularity/kit_rt.sif ./build_singularity/KiT-RT examples/configs/smoke_test.cfg
• python3 tools/check_smoke_output.py examples/result/smoke_test -> PASS output_files=1 csv_logs=1 mass=0.9439827
• Generated smoke outputs were removed after verification.
• git diff --check

Not Included

• Full Sphinx/ReadTheDocs build.
• Publishing GitHub releases, GHCR images, SIF artifacts, or checksums. Those require release/registry credentials.
• Existing unrelated untracked build directories and local SIF artifacts were left untouched.