chore: replace npm i with npm ci --ignore-scripts

[rensvmoorsel]

No description provided.

[SilasPeters]

Other places might also download node packages, like the systemd service for backup-to-s3

[SilasPeters]

What needs to be done before we merge:

• Replace all npm install with npm ci --no-scripts
• Secure all other places where node is used (npx, npm exec, others?)
• Secure dockerfiles for images used on sadserver (thus possibly requiring changes in other repositories)

[SilasPeters]

Additions: fancy-index build script, and the radio rebuild handler