refactor: static content assets directory

[Schwehn42]

Description

Resolves #4736

Changelog

• Move timer_finished.mp3 and hotkeys.pdf from public to public/assets
• Adjust path refs
• add paths to Caddy and Traefik configs

[Schwehn42]

Q: is /assets or /static better fitting?

[brandstetterm]

Q: is /assets or /static better fitting?

Fine with both

[github-actions]

The deployment to the dev cluster was successful. You can find the deployment here: https://4775.development.scrumlr.fra.ics.inovex.io
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Deployed Images

• ghcr.io/inovex/scrumlr.io/scrumlr-frontend:sha-033885f

• ghcr.io/inovex/scrumlr.io/scrumlr-server:sha-033885f

[octomind-dev]

🐙 Octomind

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commit sha: 033885f