Stabilize the extension runtime and UI

[jimscard]

Summary

• update the builder/runtime images and UI lockfile resolutions to eliminate current critical CVEs in the extension build
• create and chown the Tailscale state/socket directories before switching to the non-root runtime user so tailscaled can start reliably
• normalize Docker Desktop container payloads before rendering so containers with Ports: null do not crash the Tailscale tab
• update the CI checkout action to the current major version

Context

After updating the bundled Tailscale binary, the extension was hitting two regressions locally: the VM service exited because /var/run/tailscale did not exist for the non-root user, and the UI tab rendered blank because some real Docker Desktop container payloads include Ports: null, which the table view treated as an array.

Validation

• yarn --cwd ui lint
• yarn --cwd ui build
• docker build --tag=tailscale/docker-extension-dev .
• docker extension update --force tailscale/docker-extension-dev