feat: encapsulate identity with better-auth

platform/server/server.ts

@@ -1,4 +1,4 @@
-import "./types.d.ts";
+import "./types.ts";
 
 import { context } from "@platform/relay";
 import { InternalServerError } from "@platform/relay";

platform/server/types.ts

@@ -30,7 +30,6 @@ declare module "@platform/storage" {
 
 declare module "@platform/relay" {
   interface ServerContext {
-    isAuthenticated: boolean;
     request: {
       headers: Headers;
     };