DN-6: Replace stale Thinkster footer attribution with Conduit copyright and repo link

[devin-ai-integration]

Summary

Fixes DN-6. The site footer still showed the upstream template text ("An interactive learning project from Thinkster...") on every page. Footer.tsx (the only file changed) now renders:

© {new Date().getFullYear()} {APP_NAME} · Spring Boot 2.6.3 / Java 11 monolith · <a href=REPO_URL target="_blank" rel="noopener noreferrer">GitHub</a>

• APP_NAME is imported from lib/utils/constant.ts (value is conduit, lowercase, so the footer reads © 2026 conduit ...; matches the lowercase logo-font branding used elsewhere).
• The conduit logo link on the left and the footer markup/classes are unchanged; no CSS touched.
• cd frontend && npm run build passes (Node 16) with no TypeScript errors.

Screenshots

Before — home (/)

After — home (/)

Before — article (/article/docker-for-java-developers)

After — article (/article/docker-for-java-developers)

Link to Devin session: https://partner-workshops.devinenterprise.com/sessions/53ddbaeac9f542ba9bf4221060941a4d
Open in Devin Desktop: https://partner-workshops.devinenterprise.com/desktop/session/53ddbaeac9f542ba9bf4221060941a4d?variant=devin

[devin-ai-integration]

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