feat: custom prefix system with effects, emoji picker and per-letter colors

- Catalog page for creating custom prefixes with text, per-letter colors, emoji icon and visual effects
- Emoji picker via @emoji-mart/react with createPortal + Shadow DOM blur fix
- Inventory prefix management (activate/deactivate/delete)
- Chat bubble rendering with multi-color prefix and effect support
- Prefix utilities (getPrefixEffectStyle, parsePrefixColors, PREFIX_EFFECT_KEYFRAMES)
- All UI text in English

src/api/inventory/IPrefixItem.ts

@@ -0,0 +1,9 @@
+export interface IPrefixItem
+{
+    id: number;
+    text: string;
+    color: string;
+    icon: string;
+    effect: string;
+    active: boolean;
+}