Add S7TypeMappingTests.cs covering ReinterpretRawValue and BoxValueForWrite —
26 tests verifying every implemented type round-trip (Bool/Byte/UInt16/Int16/
UInt32/Int32/Float32), two's-complement reinterpret semantics (ushort→short,
uint→int), unsupported-type NotSupportedException, and overflow edge cases.
These methods were factored out as internal static in the S7-002/S7-008 commit.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>