chore: Add GitHub Action for spell checking with cspell

[Copilot]

Closes #147

Adds a GitHub Actions workflow to run cspell on pull requests and pushes to main. Uses the existing cspell.json configuration and .cspell/ custom dictionaries already in the repository.

• Creates .github/workflows/spellcheck.yml using streetsidesoftware/cspell-action@v6
• Checks all .html and .md files
• Includes explicit permissions: contents: read per security best practices
• Updates CONTRIBUTING.md with instructions for using cspell with Visual Studio Code (Code Spell Checker extension)
• Fixes pre-existing spelling error in CONTRIBUTING.md ("Spftware" → "Software")

The following tasks have been completed:

• Modified Web platform tests (link)

Implementation commitment:

• WebKit (link to issue)
• Chromium (link to issue)
• Gecko (link to issue)

Documentation and checks

• Affects privacy
• Affects security
• Pinged MDN
• Updated Explainer
• Updated digitalcredentials.dev

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[marcoscaceres]

@copilot, can you make the commit message start with "chore: "?

[Copilot]

@copilot, can you make the commit message start with "chore: "?

I'm unable to amend existing commit messages since that would require force pushing, which isn't available in my environment. The commit message convention could be applied when squash-merging this PR - GitHub allows you to edit the final commit message during the merge.

[marcoscaceres]

@copilot, no problem. Will fix it when I merge.

[Copilot]

Pull request overview

This PR adds automated spell checking to the repository using GitHub Actions. It leverages the existing cspell configuration (cspell.json and .cspell/ custom dictionaries) to check spelling on pull requests and pushes to the main branch.

Key Changes:

• Creates a new GitHub Actions workflow that runs cspell using the streetsidesoftware/cspell-action@v6
• Configures the workflow to check all HTML and Markdown files across the repository
• Implements minimal permissions (contents: read) following security best practices

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[marcoscaceres]

@copilot, can you also update CONTRIBUTING.md with instructions of how to use cspell with Visual Studio Code? Can you verify if you need to install "Code Spell Checker" https://marketplace.visualstudio.com/items?itemName=streetsidesoftware.code-spell-checker

[Copilot]

@copilot, can you also update CONTRIBUTING.md with instructions of how to use cspell with Visual Studio Code? Can you verify if you need to install "Code Spell Checker" https://marketplace.visualstudi...

Done in 33e2768. Added instructions to CONTRIBUTING.md for using cspell with VS Code. Yes, the "Code Spell Checker" extension is required - it's the VS Code integration for cspell and automatically reads the cspell.json configuration file in the repository. Also fixed a pre-existing typo ("Spftware" → "Software") in the same file.

[marcoscaceres]

hehe, it works! 🥳