Add Clanker Vision box runtime

[bgdnvk]

Summary

• add the native clanker-vision Clanker Box runtime
• add constrained browser, office, email draft, install, status, and stop actions
• add visible pointer/screenshot metadata plus policy gates for credentials, send/submit/delete/install-like actions
• install Chromium, Playwright, and LibreOffice support in the Clanker Box image

Tests

• go test ./internal/clankerbox
• go test ./...
• git diff --check