feat(support): add MacroColorConverter utility

app/Support/MacroColorConverter.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace App\Support;
+
+final class MacroColorConverter
+{
+    public static function fromRgba(?array $rgba): ?string
+    {
+        if ($rgba === null) {
+            return null;
+        }
+
+        return sprintf(
+            '#%02X%02X%02X',
+            (int) round(max(0.0, min(1.0, $rgba['r'])) * 255),
+            (int) round(max(0.0, min(1.0, $rgba['g'])) * 255),
+            (int) round(max(0.0, min(1.0, $rgba['b'])) * 255),
+        );
+    }
+}

tests/Unit/Support/MacroColorConverterTest.php

@@ -0,0 +1,27 @@
+<?php
+
+use App\Support\MacroColorConverter;
+
+test('converts rgba floats to hex string', function () {
+    expect(MacroColorConverter::fromRgba(['r' => 1.0, 'g' => 0.0, 'b' => 0.5, 'a' => 1.0]))->toBe('#FF0080');
+});
+
+test('converts pure black', function () {
+    expect(MacroColorConverter::fromRgba(['r' => 0.0, 'g' => 0.0, 'b' => 0.0, 'a' => 1.0]))->toBe('#000000');
+});
+
+test('converts pure white', function () {
+    expect(MacroColorConverter::fromRgba(['r' => 1.0, 'g' => 1.0, 'b' => 1.0, 'a' => 1.0]))->toBe('#FFFFFF');
+});
+
+test('converts grey', function () {
+    expect(MacroColorConverter::fromRgba(['r' => 0.5, 'g' => 0.5, 'b' => 0.5, 'a' => 1.0]))->toBe('#808080');
+});
+
+test('clamps out-of-range values', function () {
+    expect(MacroColorConverter::fromRgba(['r' => 1.5, 'g' => -0.1, 'b' => 0.5, 'a' => 0.0]))->toBe('#FF0080');
+});
+
+test('returns null for null input', function () {
+    expect(MacroColorConverter::fromRgba(null))->toBeNull();
+});