feat: add codespell linter

[lsorber]

Closes #14.

Changes:

• Add codespell linter.

[Copilot]

Pull request overview

This PR adds the codespell linter to the Substrate Python project template to help catch spelling mistakes in code, comments, and documentation.

• Adds codespell as a development dependency with version constraint >=2.4.1
• Configures codespell with appropriate built-in dictionaries and file/directory exclusions
• Integrates codespell into the pre-commit workflow to check markdown, Python, TOML, and YAML files

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
template/pyproject.toml.jinja	Adds codespell dev dependency and configuration section with built-in dictionaries, filename checking, and skip patterns
template/.pre-commit-config.yaml.jinja	Adds codespell hook to pre-commit configuration with appropriate file type filters

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