escape (25.3a): which allocations never outlive their frame - the analysis, behind --escape-report; @alloc_ok on generics

emit_escape.ludic: every value is in a class, joined by flow edges (a let, an assignment, an argument
into its parameter, a result into the call) and store edges (a field, an element, a push). HEAP (a
parameter, a state, a global, what an unknown call hands back) flows forward; ESC (stored into
something HEAP, into a global, into an event's fields or named values, handed to an unknown callee)
flows backward, and from an ESC or HEAP target along a store. A load is its base's class. A site that
is neither ESC nor in a function reaching Mem.frame is LOCAL (Node.uns = ES_SCRATCH). ludicc
--escape-report prints each site and the totals; nothing is emitted differently yet - the arena that
allocates the LOCAL sites is next.

@alloc_ok on a generic now covers its instances (kept_push$NetFact is under kept_push's), and a
statement's @alloc_ok is carried on the node (Node.uns), so a generic's clone keeps it.

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

selfhost/frontend/parse.ludic

@@ -483,7 +483,7 @@ function stmt() -> Node {
   let ln = toks[pi].line
   let n = stmt_body()
   if n.line == 0 { n.line = ln }
-  if aok { push(g_aok_nodes, n) }
+  if aok { n.uns = FR_AOK_STMT;  g_aok_seen = true }                # on the node, so a generic's clone carries it (gen_clone copies uns)
   return n
 }