repo refactor: Repair mainline benchmark hygiene and make benchmark/report artifacts reproducible from a fresh clone

[Aroesler1]

Repo job repo_refactor for objective #38 is ready for review and merge.

Objective: Build project: Real-Time Limit Order Book Engine in C++

Job instructions:
Starting from main, remove any git-tracked generated build artifacts and ensure build outputs are ignored. Reconcile the previously dirty benchmark/report state so the repository contains only source datasets, scripts, reports, and code needed for reproducible benchmarking. Verify the benchmark binaries, correctness verifier, and report-generation commands configure/build/run successfully from a fresh clone using documented commands. If benchmark datasets for AAPL plus the additional tickers are synthetic or reduced, document that clearly in repo-visible artifacts rather than implying full LOBSTER distribution data. Update README/benchmark docs only as needed to reflect the exact runnable command set on main.

Why this PR looks credible:
Tests passed on the current branch. The change is coherent and appropriately bounded for the benchmark-hygiene task. It hardens ignore rules for generated CMake/build/test/benchmark byproducts, updates repo-visible docs to describe an actually reproducible fresh-clone workflow, and clearly corrects the dataset framing so the checked-in CSVs are presented as reduced/synthetic fixtures rather than full LOBSTER distributions. The reported validation covers clean configure/build, ctest including the benchmark smoke path, the required pytest command, and all four documented benchmark invocations from an isolated copy, which is sufficient for this cleanup-focused refactor. Audit cleared the diff, with 1 remaining validation gap(s) to watch. Backend verification returned insufficient evidence.

Audit summary:
The change is coherent and appropriately bounded for the benchmark-hygiene task. It hardens ignore rules for generated CMake/build/test/benchmark byproducts, updates repo-visible docs to describe an actually reproducible fresh-clone workflow, and clearly corrects the dataset framing so the checked-in CSVs are presented as reduced/synthetic fixtures rather than full LOBSTER distributions. The reported validation covers clean configure/build, ctest including the benchmark smoke path, the required pytest command, and all four documented benchmark invocations from an isolated copy, which is sufficient for this cleanup-focused refactor.

Audit must-fix items:

• None

Validation gaps:

• The audit evidence references successful isolated-copy verification, but does not include a direct before/after inventory of any git-tracked generated artifacts that were removed; if maintainers know such files existed historically, they may still want to sanity-check git ls-files for old build outputs before merging.

[Copilot]

Pull request overview

Refactors benchmark/reproducibility documentation and ignore rules so benchmarking and report-related artifacts are reproducible from a clean clone without committing generated outputs.

Changes:

• Update report/benchmark_report.md to be a hand-maintained reproducibility note (no checked-in generated benchmark outputs).
• Update README.md to document a fresh-clone workflow using an out-of-tree temp build dir plus CTest + pytest verification.
• Expand .gitignore to cover common CMake/build outputs and generated benchmark/report artifacts.

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated no comments.

File	Description
report/benchmark_report.md	Reframes the report as a reproducibility note; documents fixture scope and the fresh-clone run sequence/commands.
README.md	Aligns top-level docs with the “fresh clone” reproducible build/test/benchmark workflow and clarifies fixture vs proprietary dataset scope.
.gitignore	Adds comprehensive ignore rules for build trees, binaries, and generated benchmark/report byproducts.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.