wcc: Hare-style enum [storage] { ... } type

`type Foo = enum [intT] { NAME [= expr], ... };`. Storage defaults
to i32; members auto-increment from 0 (or last+1) when `= expr` is
omitted, and value expressions can reference earlier siblings —
enough surface for io::mode-style flag enums (`RDWR = READ | WRITE`).

`Foo.MEMBER` folds to an N_INTLIT in the checker, typed as the
named enum. Binops on enum values yield the same enum (type_eq on
the named pointer), so `mode.R | mode.W` is a `mode`. Enum ↔ int
is a reinterpret-only `as` cast — same register, no tag wrap — so
`mode.RDWR as i32` and `1 as mode` both work without runtime ops.

`is`/`?`/`!` are still tagged-union-only. CSP runtime (chan/proc)
is unchanged; only the type-system slot is touched here.

test/wcc/300_check.c

@@ -162,6 +162,23 @@ static const struct row rows[] = {
 	  "case str | f64 => return 9; case let b: bool => return 1; }; "
 	  "return 0; };",
 	  "case: f64 is not a variant" },
+
+	/* enum types */
+	{ "type color = enum { RED, GREEN, BLUE };\n"
+	  "fn f() i32 = { return color.GREEN as i32; };", "ok" },
+	{ "type mode = enum u8 { R = 1, W = 2, RW = R | W };\n"
+	  "fn f() i32 = { let m: mode = mode.RW; return m as i32; };", "ok" },
+	{ "type mode = enum u8 { R = 1, W = 2 };\n"
+	  "fn f() i32 = { return (mode.R | mode.W) as i32; };", "ok" },
+	{ "type c = enum { A, B };\n"
+	  "fn f() i32 = { return c.NOPE as i32; };",
+	  "no enum member 'NOPE'" },
+	{ "type c = enum { A, A };\n"
+	  "fn f() i32 = { return c.A as i32; };",
+	  "duplicate enum member" },
+	{ "type c = enum bool { A };\n"
+	  "fn f() i32 = { return c.A as i32; };",
+	  "enum storage type must be integer" },
 };
 
 int