feat(wallguard): replay professional workroom contract

[mdheller]

Summary

Fresh replay of #517 onto the current Prophet Platform main-line base.

This PR preserves the WallGuard Professional Workroom product-contract slice while avoiding the stale/non-mergeable #517 branch state.

Captured from #517

• contracts/wallguard/professional-workroom.example.json
• tools/validate_wallguard_professional_workroom.py
• Makefile target wiring for validate-wallguard-professional-workroom

Boundary

• Contract/fixture validation only.
• No live UI implementation.
• No middleware implementation.
• No policy evaluation implementation.
• No runtime enforcement implementation.
• No service endpoints.
• No database schema.
• No deployment wiring.

Validation target

make validate-wallguard-professional-workroom

Supersedes

Supersedes stale/non-mergeable #517 after content replay.