wip(0.S3): ui blocks, scene on enter/exit, hooks, machines over a state's field, namespace and engine-system injection; a reference out of a read-only state or a module let is read-only; deps counts writes into another module's state; the rejected examples hold states

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

examples/rejected/friend_scope.ludic

@@ -3,8 +3,8 @@ import "private_bank"
 import "private_kit"
 program FriendScope {
   friend module lab of kit
-  entry {
-    add(5)
-    print(total())
+  entry (bank_st: mut BankState) {
+    add(bank_st, 5)
+    print(total(bank_st))
   }
 }