Added additional test coverage and updating documentation

[sn]

This pull request introduces several improvements and updates across the codebase, focusing on dependency management, documentation, and testing. The most significant changes include adding a comprehensive test suite for the Env class, updating project metadata and URLs, and refining documentation to reflect the latest project structure and ecosystem.

Testing Improvements:

• Added a new tests/test_env.py file containing thorough unit tests for the Env class, covering attribute access, the get() method, production/development mode detection, lazy loading behavior, and dotenv integration.

Dependency and Configuration Updates:

• Updated the Python setup action in .github/workflows/test.yml from actions/setup-python@v3 to v5 for improved CI reliability.
• Added pytest-cov to the optional dev dependencies in pyproject.toml to enable test coverage reporting.
• Changed the license classifier from MIT to BSD in pyproject.toml to match the project's licensing.
• Updated project URLs in pyproject.toml to use the new nitrosh GitHub organization.

Documentation Updates:

• Updated all references in README.md and pyproject.toml from nitro-sh to nitrosh, and revised ecosystem descriptions to match the latest features and repositories. [1] [2] [3]
• Added nitro-image to the ecosystem list in both README.md and the default template readme, highlighting new image optimization capabilities. [1] [2]
• Fixed a table formatting issue in SKILL.md for improved readability.
• Updated the version number in SKILL.md to 1.0.10.