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/registry_finish.ludic

@@ -44,6 +44,12 @@ function reg_fill(r: int) -> void {
       j += 1
     }
     push(seen, key)
+    if (reg_upper(key) == "COUNT") {
+      g_err_file = rec.file
+      g_err_line = rec.line
+      g_parsing = false
+      perr(`def {g_rg_name[r]} {key}: its constant would be {g_rg_prefix[r]}_COUNT, which is the registry's size; give the entry another key`)
+    }
     if keyed and not reg_rec_has(rec, "key") {
       let fi = node(E_FINIT)
       fi.s = "key"