move ruff configuration into pyproject.toml

[jameslamb]

Description

Moves ruff configuration into pyproject.toml.

I noticed this project has a .flake8, but doesn't actually run flake8 directly... I think the configuration in that .flake8 is getting ignored (based on https://docs.astral.sh/ruff/configuration/, I don't believe ruff reads .flake8 files).

This PR ensures ruff respects this project's configuration. Any other changes were made automatically by pre-commit hooks.

Issue

N/A

Notes for Reviewers

How I chose these checks

I only selected checks that flake8 would run.

I think it'd be worthwhile to expand this in the future, especially with (B) flake8-bugbear and (PERF) perflint. I'll leave that to you all in a follow-up if you'd like. Here's a list of rules I like to use in Python projects: https://github.com/jameslamb/pydistcheck/blob/3bf39fd2f0c9328e519b8892b6dfde029381d7a0/pyproject.toml#L133

Checklist

• I am familiar with the Contributing Guidelines.
• Testing
  • New or existing tests cover these changes
• Documentation
  • The documentation is up to date with these changes

Summary by CodeRabbit

• Chores

  • Removed flake8 configuration file and related ownership settings
  • Updated copyright year to 2026

• Documentation

  • Updated CuOpt documentation version to 26.04.00

• Style

  • Improved regex string literal formatting

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[jameslamb]

This change was made by just running pre-commit run --all-files. I'm not sure what's causing it.

[coderabbitai]

📝 Walkthrough

Walkthrough

The PR removes the flake8 configuration file and its references, migrates linting rules to ruff configuration in pyproject.toml, updates copyright year to 2026 across pre-commit and utility files, and updates CuOpt documentation version from 26.02.00 to 26.04.00.

Changes

Cohort / File(s)	Summary
Linting Configuration Migration .flake8, .github/CODEOWNERS, .pre-commit-config.yaml, pyproject.toml	Removed flake8 config file and CODEOWNERS reference. Expanded ruff-check arguments in pre-commit to include --config pointing to pyproject.toml. Added new [tool.ruff.lint] section with select and ignore rules, migrating from flake8-based linting.
Metadata & Utility Updates ci/utils/nbtestlog2junitxml.py	Converted regex string literals to raw strings (STARTING, SKIPPING, EXIT CODE, FOLDER, real time patterns). Updated SPDX copyright year from 2025 to 2026.
Documentation Version .pre-commit-config.yaml, docs/cuopt/source/versions1.json	Updated copyright year from 2025 to 2026 in pre-commit config. Updated CuOpt docs latest version from 26.02.00 (external URL) to 26.04.00 (relative URL); archived 26.02.00 as previous version.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: moving ruff configuration from .flake8 to pyproject.toml, which is the primary objective reflected in the file modifications.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

• 📝 Generate docstrings

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}