chore(docs): validate all internal documentation links, fix existing broken links

[mkurapov]

Changes proposed in this pull request

• Add starlight-links-validator package to our docs package (to prevent doc builds with broken links)
• Fix all broken internal links

Context

Fixes #2726

Checklist

• [x] Related issues linked using fixes #number
• [ ] Tests added/updated
• [x] Documentation added
• [ ] Make sure that all checks pass
• [ ] Bruno collection updated

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