chore(release): bump version to v2026.4.620 and update changelog}
- Bump package version from v2026.4.618 to v2026.4.620
- Update p3x-redis-ui-material dependency from ^2026.4.389 to ^2026.4.391
- Update p3x-redis-ui-server dependency from ^2026.4.329 to ^2026.4.330
- Update yarn.lock with new dependency resolutions
- Update build version references across README, artifacts, changelogs, and contributors docs