style(admin): default brand hue to Figma purple

Move purple (h277 c0.177 = #5559CE) to first HUES entry so fresh users
get the tauri purple by default; color picker retained.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

assets/admin/stores/uiStore.ts

@@ -2,10 +2,10 @@ import { create } from 'zustand';
 import { persist } from 'zustand/middleware';
 
 export const HUES = [
+  { name: 'بنفش',       h: 277, c: 0.177 },
   { name: 'آبی پزشکی',  h: 256, c: 0.15 },
   { name: 'فیروزه‌ای',  h: 205, c: 0.12 },
   { name: 'سبز سلامت', h: 162, c: 0.13 },
-  { name: 'بنفش',       h: 295, c: 0.15 },
   { name: 'نیلی',       h: 272, c: 0.16 },
 ] as const;