Introduce devcontainer to repository

[davidpirogov]

Description

Added devcontainer configuration for a consistent development environment.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring (no functional changes)
• Performance improvement
• Test coverage improvement

Related Issues

No related issues

Changes Made

• Removed .python-version in favor of uv /app/.venv approach
• Added .devcontainer/Dockerfile which sets up uv and consistent environment with devcontainer.json
• Added example documentation for developers

SPEC Compliance

• This PR implements/fixes spec compliance
• Spec section(s) affected:
• Spec version:

Testing

• All existing tests pass
• Added new tests for changes
• Tested on Python 3.8
• Tested on Python 3.9
• Tested on Python 3.10
• Tested on Python 3.11
• Tested on Python 3.12

Test Output

# Paste test output here

Code Quality

• Ran ruff check src/toon_format tests - no issues
• Ran ruff format src/toon_format tests - code formatted
• Ran mypy src/toon_format - no critical errors
• All tests pass: pytest tests/ -v

Checklist

• My code follows the project's coding standards (PEP 8, line length 100)
• I have added type hints to new code
• I have added tests that prove my fix/feature works
• New and existing tests pass locally
• I have updated documentation (README.md, CLAUDE.md if needed)
• My changes do not introduce new dependencies
• I have maintained Python 3.8+ compatibility
• I have reviewed the TOON specification for relevant sections

Performance Impact

• No performance impact
• Performance improvement (describe below)
• Potential performance regression (describe and justify below)

Breaking Changes

• No breaking changes
• Breaking changes (describe migration path below)

Screenshots / Examples

# Example usage

Output:

# Example output

Additional Context

Checklist for Reviewers

• Code changes are clear and well-documented
• Tests adequately cover the changes
• Documentation is updated
• No security concerns
• Follows TOON specification
• Backward compatible (or breaking changes are justified and documented)

[johannschopplich]

LGTM – but not my decision at all. :)

[davidpirogov]

Need one more approval from @toon-format/python-maintainers please

[Justar96]

maybe keep .python-version and update it with clear use for local development and doesn't conflict with dev container