Register bundle artifact hooks early

[chubes4]

Summary

• Register Data Machine Code bundle artifact hooks at plugin load time so Data Machine can validate DMC-owned bundle artifacts on early import paths.
• Add a smoke test covering workspace preload artifact type registration before DMC bootstrap runs.

Testing

• php -l data-machine-code.php && php -l tests/smoke-bundle-artifact-early-registration.php && php -l tests/smoke-workspace-preload-artifact.php
• php tests/smoke-bundle-artifact-early-registration.php
• php tests/smoke-workspace-preload-artifact.php
• git diff --check

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (openai/gpt-5.5)
• Used for: Diagnosed the bundle artifact registration timing failure, drafted the minimal code/test change, and ran focused verification. Chris remains responsible for review and merge.