feat: add cross-asset P1-P5 terminal contracts

[Pigbibi]

Summary

• add one shared US/CN/HK/Crypto P1-P3 research terminal contract
• add a separate no-order P4/P5 forward and portfolio-risk observation contract
• bind P4/P5 to the immutable P1-P3 terminal digest and candidate identity
• fail closed on missing, stale, malformed, or dependency-skipping artifacts
• document that paper is optional and does not grant broker or live authority

Safety boundary

• no_order=true
• permission_effect=none
• broker_dependency=false
• no broker, live, capital, leverage, or runtime changes

Validation

• 34 cross-asset driver tests passed
• 10 matrix/risk regression tests passed
• Ruff, py_compile, JSON parse, and git diff checks passed