Add table of contents to Overview page

[kcmartin]

Summary

• Enables the table of contents on the main Overview page for consistency with other documentation pages
• Removes tableOfContents: false from frontmatter, allowing Starlight's default TOC behavior
• change link card section title to "Next Steps"

Test plan

• Visit the Overview page and verify the TOC appears on the right side
• Confirm TOC includes: What makes Sprites different?, Use Cases, Core Concepts (with sub-items), Next steps

🤖 Generated with Claude Code

[github-actions]

CLI Documentation Generator

Metric	Value
CLI Version	0.0.1
Commands Generated	24
Tests	✅ 0/0 passed

📚 Commands documented

• sprite login
• sprite logout
• sprite org auth
• sprite org list
• sprite org logout
• sprite org keyring disable
• sprite org keyring enable
• sprite auth setup
• sprite create
• sprite use
• sprite list
• sprite destroy
• sprite exec
• sprite console
• sprite checkpoint create
• sprite checkpoint list
• sprite checkpoint info
• sprite checkpoint delete
• sprite restore
• sprite proxy
• sprite url
• sprite url update
• sprite api
• sprite upgrade

[github-actions]

Preview Deployment

Name	URL
Preview	https://pr-108-superfly-sprites-docs.fly.dev

Commit: 477178e

[github-actions]

Lighthouse Results

URL	Performance	Accessibility	Best Practices	SEO
/	🟠 89	🟢 100	🟢 96	🟢 100

[github-actions]

E2E Test Results

✅ Tests success

Ran against: https://pr-108-superfly-sprites-docs.fly.dev