Fix type: use StackServerApp<true, "internal"> to preserve internal user type

The getStackServerApp() was typed as plain StackServerApp (defaults to
<boolean, string>), losing the 'internal' ProjectId type parameter.
This caused getUser() to return CurrentServerUser instead of
CurrentInternalServerUser, which doesn't have listOwnedProjects.

Co-Authored-By: Konstantin Wohlwend <n2d4xc@gmail.com>

Author: devin-ai-integration[bot]

apps/dashboard/src/stack/server.tsx

@@ -5,9 +5,10 @@ import { StackServerApp } from "@stackframe/stack";
 import { StackAssertionError } from "@stackframe/stack-shared/dist/utils/errors";
 import { stackClientApp } from "./client";
 
-let _stackServerApp: StackServerApp | undefined;
+type InternalServerApp = StackServerApp<true, "internal">;
+let _stackServerApp: InternalServerApp | undefined;
 
-export function getStackServerApp(): StackServerApp {
+export function getStackServerApp(): InternalServerApp {
   if (!_stackServerApp) {
     if (isRemoteDevelopmentEnvironmentEnabled()) {
       throw new StackAssertionError("stackServerApp is not available in the local remote development environment dashboard.");