Normalize static site generator settings

[MicrowaveDev]

Source of truth

Closes #494. Static-site generator settings should be normalized, validated, and persisted as the exact options used for rendering.

Summary

• Normalizes numeric render settings with bounded defaults before queueing or rendering static sites.
• Validates top-level and nested static-site names, bounds custom CSS, and returns a clear missing-site error on update.
• Persists the normalized render options and adds focused static-site generator regression coverage.
• Updates docs/todo.md with the implemented Improve static site generator settings #494 settings slice.

Verification

• git diff --check
• node --import tsx --experimental-global-customevent -e "await import('./app/modules/staticSiteGenerator/index.ts'); console.log('static site generator import ok')"
• npm run test:docker (68 passing, 11 pending)

Closes #494