fix: set default sparkEnabled to false for unknown accounts

The fallback default account in session context had sparkEnabled: true,
which contradicts the new whitelist-only-for-pro policy introduced in
readCodexAccountSnapshot. When account/read fails during session startup,
the stale default would incorrectly allow spark model access for users
without a confirmed pro plan.

Author: cursoragent

apps/server/src/codexAppServerManager.ts

@@ -480,7 +480,7 @@ export class CodexAppServerManager extends EventEmitter<CodexAppServerManagerEve
         account: {
           type: "unknown",
           planType: null,
-          sparkEnabled: true,
+          sparkEnabled: false,
         },
         child,
         output,