[P0][DET] Classify workspace crates in det-policy.yaml

[flyingrobots]

Owner: Architect\nEstimate: 3h\nAC:\n- every crate classified once: DET_CRITICAL/IMPORTANT/NONCRITICAL\n- schema validation in CI\n- owners for DET_CRITICAL

[flyingrobots]

det-policy.yaml classifies all 28 workspace crates: 14 DET_CRITICAL, 11 DET_IMPORTANT, 3 DET_NONCRITICAL. Gate requirements assigned per tier.