Этап 2

Minint.Core/Services/IPaletteService.cs

@@ -0,0 +1,23 @@
+using Minint.Core.Models;
+
+namespace Minint.Core.Services;
+
+public interface IPaletteService
+{
+    /// <summary>
+    /// Returns the index of <paramref name="color"/> in the document palette.
+    /// If the color is not present, appends it and returns the new index.
+    /// </summary>
+    int EnsureColor(MinintDocument document, RgbaColor color);
+
+    /// <summary>
+    /// Finds index of an exact color match, or returns -1 if not found.
+    /// </summary>
+    int FindColor(MinintDocument document, RgbaColor color);
+
+    /// <summary>
+    /// Removes unused colors from the palette and remaps all layer pixel indices.
+    /// Index 0 (transparent) is always preserved.
+    /// </summary>
+    void CompactPalette(MinintDocument document);
+}