fix(lang): the action drain is the program's; --check runs every check a build makes; a registry key named count is refused; name lookups are tables

- the function that calls every reducer (and the action queue) is written in the program's own
  file: in the first action's file it belonged to that module, depended on every module with a
  reducer, and joined a game's modules into one 69-module cycle (examples/actions/modules and a
  ludic deps case hold it); the state instances, the queue and the reducers make no deps edges
- ludicc --check / ludic build --check lower the program too and write nothing, so the code
  writer's refusals are in it: a bind to a function that is gone, an unknown name (and the checker
  now refuses fn <missing> itself); rejects bind_missing_fn, unknown_name, registry_count_key
- def R count is refused: its constant would be PREFIX_COUNT, the registry's size
- a file's module, package, trust and numbers-float are tables, and from the check on the lookups
  of functions, enums, records, globals and externs are too (tagged enums kept as a list): Maroon
  Lake's check-only build went from about 20 s to 7 s including lowering, its IR from about 2
  minutes to under 10 s; duplicate declarations are found by table, not a pair of loops
- threads.ludic's pool check gives each call a little work, so a busy machine cannot run them all
  on the caller before a worker wakes (it failed one run in three under load)

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

selfhost/frontend/actions.ludic

@@ -19,6 +19,7 @@ var g_red_action: []pointer = new []pointer
 var g_dsp_ids: []Node = new []Node              # each dispatch's action number, filled at the end
 var g_dsp_names: []pointer = new []pointer
 var g_dsp_at: []Node = new []Node
+var g_act_main: pointer = null                  # the program's own file, where the drain is written
 const ACTION_PASSES: int = 64
 
 # action NAME { fields } - a record
@@ -101,12 +102,11 @@ function actions_finish() -> void {
     g_dsp_ids[i].ival = k
     i += 1
   }
+  # the queue and the drain are the program's, written in its own file: in the file of the first
+  # action they would belong to its module, and it would call every module's reducers
   var file = g_parse_file
-  var line = 1
-  if len(g_act_nodes) > 0 {
-    file = g_act_nodes[0].file
-    line = g_act_nodes[0].line
-  }
+  if g_act_main != null { file = g_act_main }
+  let line = 1
   # no actions: drain_actions() is still there (a ludic.base runner calls it), and does nothing
   if len(g_act_names) == 0 {
     vw_parse("export function drain_actions() -> void {\n}\n", file, line, 1)