docs: add product logos

[reiase]

Summary

• add Persisting, pVisor, and pChronicle icon assets to the Docusaurus static assets
• use the Persisting mark in the README and product icons in the English and Chinese product landing pages
• keep the product icon assets transparent and scoped to the documentation site

Validation

• npm --prefix docs run typecheck
• npm --prefix docs run build
• git diff --check