ci: verify clean release installations

[backnotprop]

Summary

• verify release Node packages from a clean macOS and Linux environment
• verify the immutable GHCR image through the compact Compose profile
• verify the published OpenCode adapter can be installed and loaded
• make adapter publication safe to resume after a partial npm publish
• print the browser URL from artifactserver open for automation and users

Verification

• pnpm verify:iteration
• git diff --check
• workflow YAML parse
• uvx zizmor .github/workflows

The install workflow supports both tagged releases and dry-run assets produced by the Tagged Release workflow.