TileLayer (closes#200):
- apply_threshold(source, range, tile): Set tile index where heightmap value is in range
- apply_ranges(source, ranges): Apply multiple tile assignments in one pass
ColorLayer (closes#201):
- apply_threshold(source, range, color): Set fixed color where value is in range
- apply_gradient(source, range, color_low, color_high): Interpolate colors based on value
- apply_ranges(source, ranges): Apply multiple color assignments (fixed or gradient)
All methods return self for chaining. HeightMap size must match layer dimensions.
Later ranges override earlier ones if overlapping. Cells not matching any range are unchanged.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
