fix(aws/org): reduce admin SSO session from 12h to 6h

Security review flagged 12h as excessive blast radius for a leaked
AdministratorAccess token. 6h balances hackathon workflow friction against
that risk on this personal account.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: adityataps

providers/aws/org/main.tf

@@ -46,7 +46,7 @@ resource "aws_identitystore_user" "aditya" {
 resource "aws_ssoadmin_permission_set" "admin" {
   name             = "AdministratorAccess"
   instance_arn     = local.sso_instance_arn
-  session_duration = "PT12H"
+  session_duration = "PT6H"
 }
 
 resource "aws_ssoadmin_managed_policy_attachment" "admin" {