chore: update challenges repo URL to off-on-dev/open-source-challenges

[sinduri-g]

• Replace all references to dynatrace-oss/open-ecosystem-challenges with off-on-dev/open-source-challenges across source files, tests, and docs.
• Update CODESPACES_BASE constant and orgJsonLd sameAs link accordingly.

Summary

Type of change

• feat new feature
• fix bug fix
• refactor no behavior change
• docs documentation only
• chore / config / perf / style / security

Accessibility checklist

For any change that touches the UI, copy, or routing, confirm the following before requesting review. See ACCESSIBILITY.md and the Accessibility section in CLAUDE.md for the full rules.

• Every interactive element is reachable and operable with the keyboard alone.
• Focus rings are visible in both light and dark mode (use the ring-ring token).
• One <h1> per page, no skipped heading levels.
• Every <img> has an alt attribute. Decorative images use alt="" paired with aria-hidden="true".
• Every <a target="_blank"> includes <span className="sr-only"> (opens in new tab)</span>.
• No raw Unicode symbols (such as arrows, hearts, checkmarks) used to convey meaning. Use lucide-react icons with aria-hidden, or visible text.
• Color is not the only way meaning is conveyed.
• Verified visually at mobile (375px), tablet (768px), and desktop (1280px) widths.
• If animations were added or changed, prefers-reduced-motion is respected.

Quality gates

• npm run lint passes.
• npm test passes.
• npm run build completes with no TypeScript or build errors.
• If routes were added or changed: updated public/sitemap.xml, the prerender array in react-router.config.ts, and the routes table in README.md.
• If a new component, hook, constant, or workflow was added or changed: updated styleguide.md and/or README.md per the After Making Changes section in CLAUDE.md.

Screenshots or recordings

Testing notes

[github-actions]

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2026-05-29 13:17 UTC