docs(config): consolidate and align project documentation (#112)

[nanotaboada]

Summary

• Consolidates .github/copilot-instructions.md into CLAUDE.md (verified all claims against current code before merging); deletes the legacy split-file layout
• Adds ## Invariants, ## Architecture Decision Records (forward reference to docs(adr): implement Architecture Decision Records #113), and pre-commit steps 6–7 to CLAUDE.md
• Rewrites all stale .coderabbit.yaml path instructions to reflect the current Diesel/r2d2/SQLite architecture; removes every reference to the old Mutex<Vec<Player>> in-memory design; adds missing src/repositories/**/*.rs entry; unifies tests/**/*.rs coverage

Test plan

• No regressions — purely documentation and configuration changes, no code modified
• CLAUDE.md contains all content previously in copilot-instructions.md, with the cross-language study mention removed and test helper locations verified against source
• .github/copilot-instructions.md is deleted
• .coderabbit.yaml contains no references to Mutex<Vec<Player>>, PlayerCollection::new, setup_client(), SEED_MESSI_ID, or #[patch] as a valid attribute
• CHANGELOG.md [Unreleased] updated

Closes #112

🤖 Generated with Claude Code

Summary by CodeRabbit

• Documentation

  • Added comprehensive project guide documenting architecture, guidelines, and workflows.
  • Consolidated development instructions into centralized documentation.

• Chores

  • Updated code review configuration and checklist guidelines.
  • Reorganized internal documentation structure.

[coderabbitai]

Warning

Ignoring CodeRabbit configuration file changes. For security, only the configuration from the base branch is applied for open source repositories.

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 21846779-ed47-454f-a64b-0e5cfa4121dc

📥 Commits

Reviewing files that changed from the base of the PR and between eb456f6 and 07b7a15.

📒 Files selected for processing (4)

• .coderabbit.yaml
• .github/copilot-instructions.md
• CHANGELOG.md
• CLAUDE.md

💤 Files with no reviewable changes (1)

• .github/copilot-instructions.md

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Walkthrough

The PR consolidates project documentation by replacing the split .github/copilot-instructions.md / CLAUDE.md stub layout with a single comprehensive CLAUDE.md guide, removes the now-redundant Copilot instructions file, updates .coderabbit.yaml to align its review checklist with the current Diesel/r2d2/SQLite architecture (removing stale Mutex<Vec> references), and records these changes in the changelog.

Changes

Documentation Consolidation and Alignment

Layer / File(s)	Summary
CLAUDE.md project guide creation CLAUDE.md	Creates comprehensive project documentation covering tech stack, four-layer architecture rules, keying/immutability constraints, coding and test guidelines, development commands, pre-commit checklist, Agent Mode constraints, issue templates, workflow steps, Claude Code directives, and project invariants including port, API contract stability, Conventional Commits format, and ADR forward reference.
.coderabbit.yaml review checklist alignment .coderabbit.yaml	Updates review path instructions to match current Diesel/r2d2 architecture: route handlers validate r2d2 pool State injection without PATCH, services enforce squad_number uniqueness and UUID immutability, state module describes pool initialization and embed_migrations!() startup, test instructions use current helper names (initialize_test_database, EXISTING_PLAYER_ID) and Pool::clone() for concurrency. Replaces knowledge base and finishing-touches checklist references from .github/copilot-instructions.md to CLAUDE.md.
Changelog documentation of consolidation CHANGELOG.md	Records in [Unreleased] section that agent instructions are consolidated from .github/copilot-instructions.md into CLAUDE.md and that .coderabbit.yaml is rewritten to reflect Diesel/r2d2/SQLite architecture, removing old in-memory Mutex<Vec> design references.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Assessment against linked issues

Objective	Addressed	Explanation
Verify copilot-instructions.md claims against current code and correct discrepancies [#112]	✅
Consolidate verified content into CLAUDE.md with Invariants section and ADR forward reference [#112]	✅
Delete .github/copilot-instructions.md [#112]	✅
Rewrite .coderabbit.yaml path instructions to remove in-memory architecture references and align with Diesel/r2d2/SQLite [#112]	✅
Update CHANGELOG.md [Unreleased] section [#112]	✅

Possibly related issues

• nanotaboada/go-samples-gin-restful#272: Parallel documentation consolidation effort in another repository replacing .github/copilot-instructions.md with CLAUDE.md and updating review configuration guidance.

Possibly related PRs

• nanotaboada/rust-samples-rocket-restful#46: Introduces CLAUDE.md and /precommit command integration that this PR completes by fully populating CLAUDE.md with comprehensive project guidance.
• nanotaboada/rust-samples-rocket-restful#28: Prior work reorganizing agent instructions and removing .github/copilot-instructions.md that this PR finalizes by consolidating into CLAUDE.md.
• nanotaboada/rust-samples-rocket-restful#49: Updates .coderabbit.yaml concurrency and locking guidance to reflect removal of Mutex<Vec> patterns and adoption of r2d2 pool-based concurrency semantics covered in this PR's configuration rewrites.

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The PR title follows Conventional Commits format with 'docs(config):' prefix, is 64 characters (under 80), and accurately describes the consolidation and alignment of project documentation across CLAUDE.md, .coderabbit.yaml, and deletion of copilot-instructions.md.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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📋 Issue Planner

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View plan used: #112

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch docs/consolidate-project-documentation-112

• 🛠️ sync documentation
• 🛠️ enforce http error handling
• 🛠️ idiomatic review
• 🛠️ verify api contract

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.88%. Comparing base (33d7aff) to head (07b7a15).
⚠️ Report is 10 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #114   +/-   ##
=======================================
  Coverage   84.88%   84.88%           
=======================================
  Files           6        6           
  Lines         172      172           
=======================================
  Hits          146      146           
  Misses         26       26           

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