feat(lang): bind a port member that takes nothing to a variable

bind Purse { money: g_money } writes the getter bind_Purse_money in the
bind's own file, so a one-line wrapper per member is not needed; a
member that takes something is refused a variable. Reseed.

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

selfhost/frontend/ports.ludic

@@ -2,7 +2,7 @@
 # program together, so the module never names (or `uses`) the code that answers it.
 #
 #   port Clock { now: fn() -> float, day: fn() -> int = fn default_day }    # in module clock
-#   bind Clock { now: fn game_now }                                         # in the app
+#   bind Clock { now: fn game_now, day: g_day }       # in the app; a variable for a member taking nothing
 #   Clock.now()                                                             # anywhere that sees it
 #
 # A port is a record of function values (the record `Clock_port`, members without a default are
@@ -88,6 +88,13 @@ function port_bind_one(b: Node) -> void {
     }
     i += 1
   }
+  # `member: some_global` binds a member that takes nothing to a variable: a getter is written
+  i = 0
+  while i < len(rec.kids) {
+    let e = rec.kids[i].a
+    if e != null and e.kind == E_ID { port_bind_var(b, c, rec.kids[i]) }
+    i += 1
+  }
   # what the bind names is seen from the bind's file: the port itself, and every `fn name`
   g_err_file = b.file
   g_err_line = b.line
@@ -125,6 +132,40 @@ function port_defaults_only(k: int) -> void {
   v.a = nw
   g_pt_bind[k] = nw
 }
+# `money: gm_money` for a `money: fn() -> int` member: the function `bind_<Port>_<member>` that
+# returns the variable, written in the bind's own file (so it sees what the bind sees)
+function port_bind_var(b: Node, c: Node, fi: Node) -> void {
+  let name = fi.a.s
+  let g = find_global(name)
+  if g == null { port_err(b, `bind {b.s}: {fi.s}: {name} is not a variable (a function is bound as fn {name})`) }
+  let fty = field_type(c, fi.s)
+  let n = len(fty)
+  if n < 7 or not (fty[0 .. 6] == "fn()->") {
+    port_err(b, `bind {b.s}: {fi.s} is a {fty}, and only a member that takes nothing can be bound to a variable`)
+  }
+  let ret = fty[6 .. n]
+  let gen = `bind_{b.s}_{fi.s}`
+  let src = `function {gen}() -> {ret} {{\n  return {name}\n}}\n`
+  let saved_toks = toks
+  let saved_pi = pi
+  let saved_file = g_parse_file
+  let saved_parsing = g_parsing
+  g_parse_file = b.file
+  g_parsing = true
+  lex_at(src, b.line)
+  pi = 0
+  skipnl()
+  parse_one_decl()
+  toks = saved_toks
+  pi = saved_pi
+  g_parse_file = saved_file
+  g_parsing = saved_parsing
+  let r = node(E_FNREF)
+  r.s = gen
+  r.file = b.file
+  r.line = b.line
+  fi.a = r
+}
 function ports_finish() -> void {
   let saved = g_parsing
   g_parsing = false