feat(lean): port native gates and nonlinear phase-fold proof

[barghouthi]

Summary

• Port native CCX, CCZ, and CZ optimization and exact decomposition to Lean, with gate-aware MURM synthesis bases.
• Connect randomized nonlinear phase folding to packed GF(2^128) arithmetic and prove the executable transfer, refinement, and failure bound.
• Port gate, pipeline, QASM, and PhaseFold tests, including opt-in slow parity cases.

Verification

• lake build
• lake build TzapLean.PhaseFoldSlowTests

This PR contains only the Lean commit; new planning and test-report Markdown files remain untracked.