Add dev codespace link

[andrewm4894]

Summary

• provide a badge to open a dev codespace that uses devcontainer.dev.json
• clarify how to use this configuration
• add fmt and lint helper targets in the Makefile

Testing

• pre-commit run --files README.md .devcontainer/README.md Makefile
• make tests

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https://chatgpt.com/codex/tasks/task_e_68781ba14398832899f4ecd94a70ad99

[Copilot]

Pull Request Overview

This PR enhances the development experience by adding a convenient badge for accessing a development-focused GitHub Codespace and improving development tooling. The changes provide developers with easier access to a full development environment while adding helpful code formatting and linting shortcuts.

• Adds a "Dev Codespace" badge that directly opens a codespace with the development devcontainer configuration
• Updates documentation to clarify the difference between demo and development codespace configurations
• Introduces fmt and lint Makefile targets for code formatting and linting workflows

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
README.md	Adds Dev Codespace badge and explains development environment setup
.devcontainer/README.md	Adds Dev Codespace badge and clarifies configuration selection process
Makefile	Introduces fmt and lint targets for code formatting and quality checks

[Copilot]

[nitpick] The ruff --fix command in the fmt target may overlap with the lint target's functionality. Consider using ruff check --fix . for consistency with the lint target's ruff check . pattern, or clarify the distinction between formatting fixes and linting checks.

Suggested change

	ruff --fix .
	ruff check --fix .

[github-actions]

📊 Test Coverage Report

Coverage: 63% (yellow)

✅ Coverage maintained or improved!

💡 See detailed coverage report in the tests README