escape (fix): kept memory is HEAP, so what is pushed through an alias of it is kept

render3d's stream_new holds its pool through a local (`let live = s.chunks; push(live, new
Chunk)`): the flow edge from s.chunks to live carried ESC to nothing, the Chunk records were
LOCAL, and the arena reset them under the stream - the row and horse scenarios' crash at
0xdddd... in fn_stream_update. An ESC class is now HEAP too, so every alias of kept memory is,
and a value stored through it is kept. Bidirectional alias edges were tried first and over-kept
through returns (el_place, rim).

- examples/lang/arena_alias.ludic: the stream_new shape; poisoned it read 3 3000, now 3 1518
- examples/modules/alloc_ok_private.ludic: @alloc_ok on a module's private function and on a
  statement in its private generic, declared at run time (it already passes: a guard)
- the game: frame_allocs, frame_keeps, owned_leaks 0; the lab builds under `arena strict`; the row
  scenario poisoned (R3D_ARENA_CHECK=1, 2400 frames) runs clean, bad 0 kept 0

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

selfhost/backend/emit_escape.ludic

@@ -527,6 +527,13 @@ function es_solve() -> void {
       }
       i += 1
     }
+    # kept memory outlives the frame: an ESC class is HEAP too, so every alias of it (let x = y,
+    # a load, a call's result) is, and what is stored through the alias is kept
+    i = 0
+    while i < len(g_es_flag) {
+      if (g_es_flag[i] & ES_ESC) != 0 and (g_es_flag[i] & ES_HEAP) == 0 { g_es_flag[i] = g_es_flag[i] | ES_HEAP;  changed = true }
+      i += 1
+    }
     i = 0
     while i < len(g_es_sv) {
       let v = g_es_sv[i]