docs: clarify installation instructions and notes

[Pymetheus]

Description

Update README and checklist to improve wording and installation guidance: change “Strict static typing” to “Strict static type checking” (mypy), add a link to the example project, and expand the Install & Run section to show alternative package manager commands (pip install -e ".[dev]", uv sync --extra dev, poetry install --extras dev). Also tidy a note's punctuation and update docs/CHECKLIST to use uv sync --extra dev.

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
• Code refactoring
• Performance improvement
• Test addition or update

Related Issue

no issue

Changes Made

• Update README and checklist to improve wording and installation guidance

Testing

Describe how you tested your changes:

• Unit tests pass
• Integration tests pass
• Manual testing performed

Screenshots (if applicable)

Add screenshots to help explain your changes.

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have updated the documentation accordingly
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

Additional Context

Add any other context about the PR here.

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