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.

internal/wwfixture/types.ww

@@ -1,13 +1,13 @@
 package wwfixture;
 
 def protocolversion: i32 = 1;
-def corpuscount: i32 = 1236;
+def corpuscount: i32 = 1237;
 def errorcount: i32 = 314;
 def compilecount: i32 = 12;
-def runcount: i32 = 144;
+def runcount: i32 = 145;
 def runexitcount: i32 = 766;
-def nativecount: i32 = 2472;
-def corpushash: str = "4c8f4a693d2d8193b15f4215610c1d070dc83493b1189af772ca09cad4a69db7";
+def nativecount: i32 = 2474;
+def corpushash: str = "7763f2eb34524f67355114f5bdfbf3f64415152a8ec64060fe32a322bdbe1b24";
 
 type directive = enum i32 {
 	ERROR = 0,