feat(core-trpc): scaffold tRPC client with React Query providers

- createTRPCContext + useTRPC hook for typed client access
- NextTrpcProvider with SSR-safe absolute URL resolution
- TanstackTrpcProvider for TanStack Start apps
- /api/trpc catch-all route handler in web-next
- Wire NextTrpcProvider into app providers
- Add @repo/core-trpc to transpilePackages

apps/web-next/src/app/api/trpc/[trpc]/route.ts

@@ -0,0 +1,15 @@
+import { fetchRequestHandler } from "@trpc/server/adapters/fetch";
+import { appRouter } from "@repo/core-api";
+import { bindAll } from "../../../../server/bind-production";
+
+const handler = async (req: Request) => {
+  await bindAll();
+  return fetchRequestHandler({
+    endpoint: "/api/trpc",
+    req,
+    router: appRouter,
+    createContext: () => ({}),
+  });
+};
+
+export { handler as GET, handler as POST };

apps/web-next/src/app/providers.tsx

@@ -1,5 +1,7 @@
 "use client";
 
+import { NextTrpcProvider } from "@repo/core-trpc/next";
+
 export function Providers({ children }: { children: React.ReactNode }) {
-  return <>{children}</>;
+  return <NextTrpcProvider>{children}</NextTrpcProvider>;
 }