feat: raw terrain parsing for scene data

Replace old dNavigation/dTerrain raw parser with new Raw module in
dZoneManager. Parse heightmaps, color maps, and scene maps from .raw
files to determine which scene a position belongs to. Build scene
adjacency graph from terrain data and scene transitions.

Adds NiColor type, SceneColor lookup table, eSceneType enum, terrain
mesh generation with OBJ export, and debug slash commands for scene
visualization.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

dCommon/NiColor.h

@@ -0,0 +1,34 @@
+#ifndef NICOLOR_H
+#define NICOLOR_H
+
+struct NiColor {
+	float m_Red;
+	float m_Green;
+	float m_Blue;
+
+	constexpr NiColor(float red, float green, float blue) : m_Red(red), m_Green(green), m_Blue(blue) {}
+	constexpr NiColor() : NiColor(0.0f, 0.0f, 0.0f) {}
+
+	/* reduce RGB files to grayscale, with or without alpha
+	 * using the equation given in Poynton's ColorFAQ at
+	 * <http://www.inforamp.net/~poynton/> // dead link
+	 * Copyright (c) 1998-01-04 Charles Poynton poynton at inforamp.net
+	 *
+	 *     Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
+	 *
+	 *  We approximate this with
+	 *
+	 *     Y = 0.21268 * R    + 0.7151 * G    + 0.07217 * B
+	 *
+	 *  which can be expressed with integers as
+	 *
+	 *     Y = (6969 * R + 23434 * G + 2365 * B)/32768
+	 *
+	 *  The calculation is to be done in a linear colorspace.
+	 *
+	 *  Other integer coefficents can be used via png_set_rgb_to_gray().
+	 */
+	float ToXYZ() const { return (m_Red * 0.212671f) + (m_Green * 0.71516f) + (m_Blue * 0.072169f); };
+};
+
+#endif // NICOLOR_H