chore: add chart categories to Chart type

Author: SkySails

.changeset/happy-cups-fry.md

@@ -0,0 +1,5 @@
+---
+"@navigraph/charts": patch
+---
+
+Added `ChartCategory` type for improved type-safety when dealing with chart objects.

packages/charts/src/public-types.ts

@@ -26,14 +26,16 @@ export interface BoundingBoxes {
   insets: Inset[];
 }
 
+export type ChartCategory = "APT" | "REF" | "ARR" | "DEP" | "APP";
+
 export type Chart = {
   image_day: string;
   image_night: string;
   thumb_day: string;
   thumb_night: string;
   icao_airport_identifier: string;
   id: string;
-  category: string;
+  category: ChartCategory;
   precision_approach: boolean | null;
   index_number: string;
   name: string;