Class equivalence pass: full inventory, fixtures, contracts, and 3-cycle validation

[iahncajigas]

Summary

• add class-equivalence inventory/report artifacts for all toolbox classes
• add MATLAB class fixture exporter and committed gold fixtures for class contracts
• add class contract harness/tests and artifact schema tests
• fix compatibility gap by implementing DecodingAlgorithms.getPoolSizeCompat and wiring it into behavior contracts
• run 3 full validation cycles and commit refreshed gate artifacts/logs

Commits

• 5564c73
• 6a23bc6
• cc83b76

Validation

• pytest -q
• numeric drift gate
• functional parity gate
• example output spec gate
• gate-mode validation PDF (0 parity failures, 0 uniqueness violations)
• image-mode parity (0 failing pages)
• performance parity (regression_fail=0)