feat(commands): type command payload dispatch

commands/payloads.ts

@@ -0,0 +1,16 @@
+import type {
+  ViewportPanPayload,
+  ViewportSetSizePayload,
+  ViewportSetZoomPayload,
+  ViewportZoomAroundPointPayload,
+} from "./viewport";
+
+export type CommandPayloads = {
+  "viewport.pan": ViewportPanPayload;
+  "viewport.setZoom": ViewportSetZoomPayload;
+  "viewport.zoomAroundPoint": ViewportZoomAroundPointPayload;
+  "viewport.setSize": ViewportSetSizePayload;
+  "viewport.reset": void;
+};
+
+export type CommandId = keyof CommandPayloads;