escape (fix): a function taken as a value keeps what it returns, and an entry is walked

Two more holes of the arena's family, found from ECS's births:
- a function called through a function value (UiClass.make's cmp_x_new, a step list, a System's tick)
  has its result flow nowhere the analysis can see, so what it returned looked LOCAL - and a caller
  keeping it (ludic.ui's instance table) would keep scratch. Every function taken as a value (fn f)
  now has its result kept.
- an entry block has no name, and the analysis only walked named declarations: what an entry stored
  was never seen. It is walked now.
examples/lang/arena_fnval.ludic (a factory in a field, its records kept by a pool across frames)
crashed poisoned before and prints '5 1053' as the heap does now; in ludic-dev test. Maroon Lake:
component constructors are kept, not births (birth_leaks 115 -> 103); what fn values return is kept
(frame_allocs 194 -> 210, frame_keeps 151 -> 162); 5293 sites local, 6586 kept.

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

selfhost/backend/emit_escape.ludic

@@ -31,6 +31,7 @@ var g_es_aok: int = 0                               # inside a statement under @
 var g_es_site_aok: []bool = new []bool              # the site is (not reported by the region rule)
 var g_es_site_grow: []bool = new []bool             # the site is a push's growth (25.5's capacities, not the rule)
 var g_es_done: bool = false
+var g_es_fnrefs: []pointer = new []pointer          # functions taken as values (fn f): called from anywhere
 var g_es_consumed: []Node = new []Node              # text used up where it is made (a + or == operand): freed at once
 var g_es_ft: []int = new []int                      # flow edges
 var g_es_ff: []int = new []int
@@ -175,7 +176,11 @@ function es_is_mem_frame(n: Node) -> bool {
 function es_val(e: Node) -> int {
   if e == null { return -1 }
   let k = e.kind
-  if k == E_STR or k == E_INT or k == E_BOOL or k == E_FLOAT or k == E_NULL or k == E_FNREF { return -1 }
+  if k == E_FNREF {                                # a function handed on as a value: whoever calls it keeps what it returns
+    if e.s != null { push(g_es_fnrefs, e.s) }
+    return -1
+  }
+  if k == E_STR or k == E_INT or k == E_BOOL or k == E_FLOAT or k == E_NULL { return -1 }
   if k == E_ID {
     let c = es_local(e.s)
     if c >= 0 { return c }
@@ -572,10 +577,13 @@ function escape_analyse() -> void {
   var i = 0
   while i < len(prog) {
     let d = prog[i]
-    if (d.kind == N_FN or d.kind == N_SYS or d.kind == N_MAIN) and d.s != null and ck_tab_get(g_es_fk, g_es_fv, d.s) == null {
+    # an entry has no name, and must be walked all the same: what it keeps, it keeps for good
+    var dn = d.s
+    if d.kind == N_MAIN and dn == null { dn = "$entry" }
+    if (d.kind == N_FN or d.kind == N_SYS or d.kind == N_MAIN) and dn != null and ck_tab_get(g_es_fk, g_es_fv, dn) == null {
       let h = new Node
       h.ival = len(g_es_fnode)
-      ck_tab_put(g_es_fk, g_es_fv, d.s, h)
+      ck_tab_put(g_es_fk, g_es_fv, dn, h)
       push(g_es_fnode, d)
       push(g_es_fspans, d.kind == N_MAIN)
       push(g_es_fparam, len(g_es_flag))
@@ -626,6 +634,15 @@ function escape_analyse() -> void {
     es_walk(g_onlisten[li].a)
     li += 1
   }
+  # a function taken as a value is called where the analysis cannot see (a UiClass's make, a step
+  # list, a System's tick): its result is kept by whoever calls it, whatever it returns
+  var fr = 0
+  while fr < len(g_es_fnrefs) {
+    let fs = es_fns_for(g_es_fnrefs[fr])
+    var fq = 0
+    while fq < len(fs) { es_escape(g_es_fret[fs[fq]]);  fq += 1 }
+    fr += 1
+  }
   es_solve()
   # a node analysed more than once (a field's default, walked at every `new` of its record) is
   # scratch only if every walk found it LOCAL: mark the LOCAL ones, then take the mark off any node
@@ -681,6 +698,12 @@ function escape_report() -> void {
     file_write(file_stderr(), line, len(line))
     s += 1
   }
+  var fl = 0
+  while fl < len(g_es_fnrefs) {
+    let fm = `escape: fn value {g_es_fnrefs[fl]} ({itoa(len(es_fns_for(g_es_fnrefs[fl])))} functions)\n`
+    file_write(file_stderr(), fm, len(fm))
+    fl += 1
+  }
   let tot = `escape: {itoa(g_es_local_n)} local, {itoa(g_es_esc_n)} kept\n`
   file_write(file_stderr(), tot, len(tot))
 }

selfhost/backend/emit_frame.ludic

@@ -249,7 +249,7 @@ function deps_keeps(f: pointer, seen: []bool) -> void {
   while s < len(g_es_site) {
     let c = g_es_site_cls[s]
     let fi = g_es_site_fn[s]
-    if c >= 0 and fi >= 0 and (g_es_flag[c] & ES_ESC) != 0 and not g_es_site_aok[s] and not g_es_site_grow[s] {
+    if c >= 0 and fi >= 0 and g_es_fnode[fi].s != null and (g_es_flag[c] & ES_ESC) != 0 and not g_es_site_aok[s] and not g_es_site_grow[s] {
       let d = g_es_fnode[fi]
       let k = dr_index(d.s)
       if k >= 0 and seen[k] and not fr_alloc_ok(d.s) and d.file != null and not is_runtime_file(d.file) {
@@ -319,7 +319,7 @@ function deps_births(f: pointer, seen: []bool) -> void {
     let c = g_es_site_cls[s]
     let fi = g_es_site_fn[s]
     let site = g_es_site[s]
-    if c >= 0 and fi >= 0 and (g_es_flag[c] & (ES_ESC | ES_FREED)) == 0 and not g_es_site_aok[s] and not g_es_site_grow[s] {
+    if c >= 0 and fi >= 0 and g_es_fnode[fi].s != null and (g_es_flag[c] & (ES_ESC | ES_FREED)) == 0 and not g_es_site_aok[s] and not g_es_site_grow[s] {
       let d = g_es_fnode[fi]
       let k = dr_index(d.s)
       let inframe = k >= 0 and seen[k]