Add review evidence authority foundation

[haasonsaas]

Summary

• define typed review hypotheses, evidence references, verifier identities, receipts, and compilation outcomes
• add an immutable exact-match verifier registry and deterministic, domain-separated identities
• compile only trusted deterministic verifier receipts into verified findings; semantic scouts remain advisory
• preserve existing analyzer, review-intelligence, persistence, rollout, and policy behavior

Authority boundary

This is Slice 1 of Room's evidence-compiled review system. It adds the pure contract and compiler foundation only: no external verifier execution, persistence, service integration, or new blocking policy is activated.

Malformed or mismatched authority bindings are invalid; unavailable, conflicting, or uncovered verification is indeterminate; rejected hypotheses remain finding-free. Model identity, confidence, agreement, and presentation prose cannot grant verifier authority.

Verification

• buf lint
• buf generate (clean generated output)
• go test ./...
• go test -race ./...
• go vet ./...
• golden digest fixture and repeated canonicalization tests

Room guardrail

• final diff decision: allow
• analysis status: complete
• audit event: 02e72382136432409067f2e1bb22bffe
• evaluation: f8010407b11172ce4fc5482c01ac5fd5