fix(basetype): Add min/max template functions to BaseType.h (TheSuperHackers#2183)

Add lowercase min/max template functions to BaseType.h alongside existing
uppercase MIN/MAX macros from BaseTypeCore.h.

Problem: BitFlags.h and other GameEngine code needed readable min() calls,
but VC6's <algorithm> lacks std::min/std::max. GameEngine code cannot rely
on always.h (WWVegas layer).

Solution: Add min/max templates to BaseType.h with header guard to prevent
conflicts when GameEngine code includes both BaseType.h and WWVegas headers
(which also define min/max in always.h).

Implementation:
- Use same header guard as always.h (_MIN_MAX_TEMPLATES_DEFINED_)
- Templates coexist with uppercase MIN/MAX macros
- Works with VC6, MSVC, and MinGW-w64
- Follows existing BaseType.h pattern (sqr, clamp, sign templates)

Author: JohnsterID

Core/Libraries/Include/Lib/BaseType.h

@@ -58,6 +58,28 @@ inline int sign(NUM x)
 	else return 0;
 }
 
+// TheSuperHackers @refactor JohnsterID 24/01/2026 Add lowercase min/max templates for GameEngine layer.
+// GameEngine code typically uses BaseType.h, but may include WWVegas headers (which define min/max in always.h).
+// Header guard prevents duplicate definitions. VC6's <algorithm> lacks std::min/std::max.
+#ifndef _MIN_MAX_TEMPLATES_DEFINED_
+#define _MIN_MAX_TEMPLATES_DEFINED_
+
+#ifdef min
+#undef min
+#endif
+
+#ifdef max
+#undef max
+#endif
+
+template <typename T>
+inline T min(T a, T b) { return (a < b) ? a : b; }
+
+template <typename T>
+inline T max(T a, T b) { return (a > b) ? a : b; }
+
+#endif // _MIN_MAX_TEMPLATES_DEFINED_
+
 //-----------------------------------------------------------------------------
 inline Real rad2deg(Real rad) { return rad * (180/PI); }
 inline Real deg2rad(Real rad) { return rad * (PI/180); }
@@ -179,8 +201,8 @@ struct RealRange
 	// both ranges
 	void combine( RealRange &other )
 	{
-		lo = MIN( lo, other.lo );
-		hi = MAX( hi, other.hi );
+		lo = min( lo, other.lo );
+		hi = max( hi, other.hi );
 	}
 };