feat: .deck → .contract.ts skeletal generation via TarotScript

[stackbilt-admin]

TarotScript already has:

• Recursive descent parser
• Manifest generation (property type inference from deck cards)
• DeckSlotContract validation framework

The Triad flow is: .deck (domain ontology) → .contract.ts (contract ontology) → generated code.

This issue tracks wiring TarotScript's spread engine to emit skeletal contract files from architectural spreads. Coordinate with Stackbilt-dev/tarotscript#138.

Depends on: contracts package stabilizing via FoodFiles validation (#1).