docs(skills): require GitHub API fallback for issue comments

[Gabo-Dev]

Summary

• Add a GitHub API fallback to the component-contributor and component-spec-proposer skills when the rendered issue page does not expose comments.
• Prevent the intake flow from missing validated specs that live in issue comment threads.

Closes #170

Type of change

• 🧩 New component
• 🐛 Bug fix
• 🎨 Design tokens
• ♿ Accessibility
• 🏗️ Infrastructure
• 📚 Documentation

Component checklist (skip if not applicable)

• Follows the 5-file structure (types.ts, use*.ts, Component.tsx, index.ts, *.stories.tsx)
• CVA variants defined in types.ts, not inline
• No hardcoded colors — uses tokens from theme.css
• No any types — TypeScript strict
• ARIA attributes present and correct
• Keyboard navigable (Tab, Enter, Escape where applicable)
• Dark mode works correctly
• Storybook stories cover: default, variants, states (hover, focus, disabled)
• Tests added or updated

How to test

1. Open a GitHub issue that stores the validated spec in comments.
2. Verify the skills now instruct the agent to fetch comments through the GitHub API or gh api if the rendered page does not expose them.
3. Confirm the repository still passes pnpm run typecheck via the pre-commit hook on commit.

Notes for reviewer

This change is a harness/docs correction only. No runtime component behavior changed.