fix: resolve ESLint unused variable errors

[aaron-seq]

Fixed 6 ESLint no-unused-vars errors across 4 files by prefixing unused parameters with underscores per project conventions:

• scripts/popup-main.js: Updated updatePageInfo, copyToClipboard, and calculateReadabilityScore to use underscore-prefixed params
• src/services/ai-service.js: Updated makeProviderRequest param
• tests/e2e/extension-loading.spec.js: Renamed context to _context
• tests/integration/extension-workflow.test.js: Removed unused result assignment

All unit tests pass and linting now reports 0 errors (8 acceptable warnings for console statements in logging utilities).

Description

Provide a brief description of the changes made in this pull request.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Code refactoring
• Performance improvement
• Test coverage improvement

Related Issues

• Closes #(issue number)
• Fixes #(issue number)
• Relates to #(issue number)

Changes Made

Core Changes

• List specific changes made to core functionality
• Include any architectural changes
• Note any new dependencies added

UI/UX Changes

• Describe any user interface changes
• Include screenshots if applicable
• Note any accessibility improvements

API Changes

• Document any API changes
• Note breaking changes
• Update version numbers if needed

Testing

Automated Testing

• Unit tests pass (npm test)
• E2E tests pass (npm run test:e2e)
• Coverage threshold met (npm run test:coverage)
• Linting passes (npm run lint)
• Type checking passes (npm run typecheck)

Manual Testing

• Extension loads without errors in Chrome
• Extension loads without errors in Edge
• Context menus function correctly
• Popup opens and functions correctly
• Background service worker initializes
• Content scripts inject properly
• AI providers respond correctly
• Error handling works as expected

Browser Compatibility

• Chrome (version 88+)
• Edge (version 88+)
• Tested in incognito/private mode

Security Considerations

• Input validation implemented
• XSS prevention measures in place
• API keys handled securely
• Content Security Policy updated if needed
• No sensitive data exposed in logs

Performance Impact

• No significant performance degradation
• Memory usage is reasonable
• API calls are optimized
• Caching implemented where appropriate
• Bundle size impact is minimal

Documentation

• README.md updated if needed
• CONTRIBUTING.md updated if needed
• Code comments added for complex logic
• JSDoc comments added for new functions
• CHANGELOG.md updated

Screenshots

Additional Notes

Checklist

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• 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
• Any dependent changes have been merged and published