Split consolidation proposal DTOs

[yvette-carlisle]

Summary

• Move consolidation proposal/review DTOs into types/proposals.rs
• Keep run DTOs in types/runs.rs and promotion payload/helper in parent types.rs
• Preserve the public consolidation re-export surface

Validation

• cargo make fmt-rust
• cargo make fmt-rust-check
• cargo make check-rust
• cargo make lint-vstyle
• git diff --check
• cargo make lint-rust
• cargo make test-rust (370 passed, 92 skipped)
• cargo make check (370 passed, 92 skipped)
• cargo make test-rust-integration (92 passed, 370 skipped)
• cargo make check-trace-gate
• Read-only scout and skeptic reviews