Ports three Research Stack RRC gates into formal/SilverSight/RRC/ using the existing CoreFormalism braid and Q16_16 surfaces.
Adds a Lean ↔ C ↔ Python Q16_16 roundtrip test:
- c/q16_canonical.c: canonical saturating Q16_16 C library
- exe/Q16_16Roundtrip.lean: Lake extern_lib linked executable
- tests/test_q16_roundtrip.py: Python ↔ C harness (revived from quarantine)
Updates lakefile.lean with q16-roundtrip executable and extern_lib q16_canonical.
Build: lake build SilverSightRRC 3006 jobs, 0 errors; q16-roundtrip 5949 jobs, 0 errors