add $growi-ai-purple color

.changeset/odd-ladybugs-unite.md

@@ -0,0 +1,5 @@
+---
+'@growi/core-styles': minor
+---
+
+add $growi-ai-purple color

packages/core-styles/scss/variables/_growi-official-colors.scss

@@ -1,3 +1,4 @@
 // == GROWI Official Color
 $growi-green: #7AD340;
 $growi-blue: #428DD1;
+$growi-ai-purple: #a190cd;