Add shared ItemKind Type

src/types/base/models/item-kind.ts

@@ -0,0 +1,12 @@
+import { BaseItemKind } from '@jellyfin/sdk/lib/generated-client/models/base-item-kind';
+
+export const ItemKind = {
+    ...BaseItemKind,
+    Timer: 'Timer',
+    SeriesTimer: 'SeriesTimer'
+} as const;
+
+// eslint-disable-next-line @typescript-eslint/no-redeclare
+export type ItemKind = keyof typeof ItemKind;
+
+export type ItemType = ItemKind | null | undefined;