feat(t3-app): add inference helper and example usage (#613)

* add inference helper and example usage

* my prettier is weird

* ??

Author: juliusmarminge

.changeset/spicy-falcons-poke.md

@@ -0,0 +1,5 @@
+---
+"create-t3-app": minor
+---
+
+add inference helper for v10

cli/template/addons/trpc/utils.ts

@@ -1,8 +1,11 @@
 // src/utils/trpc.ts
+import superjson from "superjson";
+
 import { httpBatchLink, loggerLink } from "@trpc/client";
 import { createTRPCNext } from "@trpc/next";
+import type { GetInferenceHelpers } from "@trpc/server";
+
 import type { AppRouter } from "../server/trpc/router/_app";
-import superjson from "superjson";
 
 const getBaseUrl = () => {
   if (typeof window !== "undefined") return ""; // browser should use relative url
@@ -28,3 +31,9 @@ export const trpc = createTRPCNext<AppRouter>({
   },
   ssr: false,
 });
+
+/**
+ * Inference helpers
+ * @example type HelloOutput = AppRouterTypes['example']['hello']['output']
+ **/
+export type AppRouterTypes = GetInferenceHelpers<AppRouter>;