Refine Copilot and CONTRIBUTING guidelines for clarity and conciseness

[Borda]

This pull request introduces significant improvements to the project's contributor and reviewer documentation. The main focus is on providing clear, actionable, and consistent guidelines for both code contributors and reviewers. The changes include a comprehensive new PR Review Guidelines section in CONTRIBUTING.md and a rewritten, more focused copilot-instructions.md that covers repository context, development workflows, code conventions, and review best practices.

The most important changes are:

PR Review Process Enhancements:

• Added a detailed "PR Review Guidelines" section to .github/CONTRIBUTING.md, outlining objectives, checklists, scoring rubrics, risk assessment, constructive feedback strategies, and a standardized review summary template to ensure actionable and high-quality reviews.

Developer and Maintainer Onboarding:

• Rewrote .github/copilot-instructions.md to provide a concise repository overview, project structure, and explicit instructions for setup, development, testing, documentation, and review processes, making onboarding easier for new contributors and maintainers.

Code Quality and Contribution Standards:

• Clarified and enforced code style, API design, performance, and documentation requirements, including mandatory Google-style docstrings with examples, type hints, and pre-commit checks for all contributions.

Testing and Documentation Requirements:

• Established explicit testing and documentation standards for new features and changes, including test coverage for edge cases and integration with project documentation and navigation.

Branching and Commit Strategy:

• Documented the required branching model and conventional commit message format to ensure consistency across all contributions.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73%. Comparing base (0ed48f0) to head (a2b7dc7).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff           @@
##           develop   #2150   +/-   ##
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  Coverage       73%     73%           
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  Files           61      61           
  Lines         7386    7386           
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  Hits          5413    5413           
  Misses        1973    1973           

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[Copilot]

Pull request overview

This pull request refines the project's contributor and reviewer documentation by consolidating and clarifying guidelines across two key files. The changes transform copilot-instructions.md from a verbose PR review guideline document into a concise, context-aware reference guide for development workflows, while moving the comprehensive PR review guidelines to CONTRIBUTING.md where they're more discoverable for human contributors and reviewers.

Changes:

• Rewrote .github/copilot-instructions.md to provide concise repository overview, project structure, development commands, code conventions, and cross-references to detailed documentation
• Added comprehensive "PR Review Guidelines" section to .github/CONTRIBUTING.md with objectives, checklists, scoring rubrics, risk assessment frameworks, and review templates
• Established consistent cross-references between documentation files to guide users to appropriate resources

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
.github/copilot-instructions.md	Completely restructured from detailed PR review guidelines to concise development context guide with commands, conventions, and cross-references
.github/CONTRIBUTING.md	Added comprehensive PR Review Guidelines section (289 lines) covering review objectives, completeness checklists, quality assessment rubrics, risk assessment, and best practices