docs: add CLAUDE.md for Claude Code guidance

[jdx]

Summary

Add CLAUDE.md file to provide context for Claude Code when working in this repository.

Contents:

• Build, test, and lint commands (including single test execution)
• Workspace structure explanation (lib, cli, clap_usage crates)
• Architecture overview covering spec model, shell completions, parsing, and docs generation
• KDL spec format example
• Testing notes (insta snapshots, shell integration requirements)
• Key dependencies

Test plan

• File created with accurate information
• All tests pass

🤖 Generated with Claude Code

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Note

Adds a contributor guidance doc for AI-assisted code workflows.

• New CLAUDE.md with project overview and goals
• Build/test/lint commands, including single-test and snapshot update flows
• Workspace structure (lib, cli, clap_usage) and high-level architecture (spec model, completion generation, argument parsing, docs generation)
• KDL spec format example
• Testing requirements and notes (shell integrations, cargo-insta)
• Key dependencies overview (kdl, clap, miette, tera, insta)

^{Written by Cursor Bugbot for commit 46db90c. This will update automatically on new commits. Configure here.}

[Copilot]

Pull request overview

This PR adds a CLAUDE.md file to provide Claude Code with essential context about the repository's structure, commands, and architecture when working with the codebase.

Changes:

• Adds comprehensive documentation covering build/test commands, workspace structure, and architecture
• Includes KDL spec format examples and testing guidelines
• Lists key dependencies and their purposes

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 47.66%. Comparing base (1a01e07) to head (0b6ebda).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #452      +/-   ##
==========================================
- Coverage   47.72%   47.66%   -0.07%     
==========================================
  Files          47       47              
  Lines        6925     6928       +3     
  Branches     6925     6928       +3     
==========================================
- Hits         3305     3302       -3     
- Misses       1777     1780       +3     
- Partials     1843     1846       +3     

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