ludic.ui: nothing a frame on the pack screen - a key's down/up carry one kept null, scroll asks filtered in place, a shadow's colour joined through the memo, numbers to 65536 made once each

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

packages/ludic.ui/backend.ludic

@@ -39,6 +39,7 @@ export state UiState {
   uv_false: Val = null
   mm: UiMemo = null                      # memo.ludic: splits, gradients and keys by their text
   mm_ints: []string = null
+  fc_none: Val = Value.null()            # focus.ludic: the value a key's down and up carry, made once
   mm_ivals: []Val = null
   ev_depth: int = 0                      # eval.ludic: a call's arguments, in lists kept one a depth
   ev_args: []Val = new []Val