feat(commands): add transparent artboard creation

commands/document.ts

@@ -0,0 +1,34 @@
+import type { Rect } from "@core/geometry";
+import type { ArtboardId } from "@core/id";
+import type { Command } from "./command";
+
+export type DocumentAddArtboardPayload = {
+  id: ArtboardId;
+  name: string;
+  bounds: Rect;
+};
+
+export const documentAddArtboardCommand: Command<DocumentAddArtboardPayload> = {
+  id: "document.addArtboard",
+  name: "Add artboard",
+  execute({ state }, payload) {
+    return {
+      ...state,
+      document: {
+        ...state.document,
+        artboards: [
+          ...state.document.artboards,
+          {
+            id: payload.id,
+            name: payload.name,
+            bounds: payload.bounds,
+            backgroundColor: "transparent",
+            layers: [],
+          },
+        ],
+      },
+    };
+  },
+};
+
+export const documentCommands = [documentAddArtboardCommand] satisfies Command<unknown>[];