check: type the N_BIN operand of as in the wwstage

An enum OR-fold under `as` ((m.A|m.B) as u32) was never typed:
scruttype resolves IDENT/DOT only, and the post-order restamp then
re-derived the folded member literals as untyped_int. The unstamped
operand missed cgtypeassert's #27b enum-reinterpret gate and lowered
as a phantom tagged assert — unconditional exit 1 at runtime on the
wwstage leg. checkisas now types an N_BIN lhs and the N_BIN restamp
preserves an existing enum stamp. Graduates the #59.9 stattest pin.

test/wcc/989_lib_byteid.c

@@ -169,8 +169,13 @@ static const struct ent ents[] = {
 	/* #59.7 siphash graduated to M_ID above (#61 fix) */
 	{ .fixture = "lib/log/logtest.ww",
 	  .mode = M_DIVERGE, .cite = "#59.8" },
+	/* #59.9 graduated: the wwstage checker never typed an N_BIN operand
+	 * of `as`, so an enum OR-fold reached cgen unstamped and lowered as
+	 * a phantom tagged assert (unconditional exit 1). checkisas now
+	 * types the N_BIN lhs and the post-order restamp preserves the enum
+	 * stamp. Runtime pin: r599_enum_orfold_as. */
 	{ .fixture = "lib/os/stattest.ww",
-	  .mode = M_DIVERGE, .cite = "#59.9" },
+	  .mode = M_ID, .cite = "#59.9 graduated by the checkisas N_BIN stamp" },
 	/* #59.10 stoftest graduated to M_ID above (#62 fix) */
 	{ .fixture = "lib/ww/syntax/toktest.ww", .inc = "lib/ww",
 	  .mode = M_ID, .cite = "#59.11 graduated by #146 str==" },

test/wcc/data/r599_enum_orfold_as/case.ww

@@ -0,0 +1,16 @@
+//ww:run
+// #59.9: an enum member OR-fold under `as`. The pre-fix wwstage
+// checker never typed the N_BIN operand, so cgtypeassert's enum
+// reinterpret gate missed and lowered a phantom tagged assert that
+// unconditionally exited 1.
+package main;
+
+type mask = enum u32 { A = 1, B = 2, C = 4 };
+
+fn main() i32 = {
+	let w: u32 = (mask.A | mask.B | mask.C) as u32;
+	if (w != 7u32) { return 1; };
+	let v: u32 = (mask.A | mask.C) as u32;
+	if (v != 5u32) { return 2; };
+	return 0;
+};