IEEE 754 number representation

Date: 2026-03-05 Area: runtime Pull Request: #39

Switch number representation from enum to IEEE 754. Removed TGocciaNumberSpecialValue enum and FSpecialValue field from TGocciaNumberLiteralValue. Numbers now store a single Double using standard IEEE 754 bit patterns for NaN, Infinity, and -0. Enabled by masking all FPU exceptions via SetExceptionMask so that operations like 0.0 / 0.0 produce IEEE 754 NaN instead of raising a Pascal exception. The IsNaN/IsInfinity/IsNegativeZero property accessors delegate to Math.IsNaN/Math.IsInfinite and an endian-neutral sign-bit check. The engine saves and restores the previous exception mask on creation/destruction. #39. value-system.md § Number Representation.