selfhost: mirror enum tokens + AST + parsetype branch

Parses byte-identical to the C frontend on enum sources (verified
via `diff` of wwdump vs wwdump_ww -a on an enum-using fixture).
The selfhost side reserves the slot in the AST and TY_* enums so
later check.ww and cgen mirror work doesn't shift numeric IDs.

Codegen-side enum support (member-value folding in cgdot, enum↔int
pass-through in cgtypeassert) is deferred — current selfhost sources
don't use enum, so 990_selfhost / 995_self_rebuild stay green.

main.combined.ww in wwdump/ and w6c/ regenerated by `ww build` as
a side effect of `make wwstage`.

lib/ww/parse/parse.ww

@@ -192,6 +192,40 @@ fn parsetype(p: *parser) *node = {
 		return n;
 	};
 
+	if (p.curkind == TK_ENUM) {
+		// `enum [storage] { NAME [= expr], ... }`
+		// Storage defaults to i32 (lhs == nil). Each member is an
+		// N_TENUMMEMBER with str=name and lhs = value expr or nil
+		// (auto-increment when omitted).
+		advance(p);
+		let n: *node = newnode(p.a, N_TENUM, pf, pl, pc);
+		if (p.curkind != TK_LBRACE) {
+			n.lhs = parsetype(p);
+		};
+		expecttok(p, TK_LBRACE, "expected '{' after enum");
+		let mhead: *node = nil;
+		let mtail: *node = nil;
+		for (p.curkind != TK_RBRACE) {
+			if (p.curkind == TK_EOF) { break; };
+			let mpf: str = p.curfile;
+			let mpl: i32 = p.curline;
+			let mpc: i32 = p.curcol;
+			let m: *node = newnode(p.a, N_TENUMMEMBER, mpf, mpl, mpc);
+			let mid: str;
+			expectident(p, &mid);
+			m.str = mid;
+			if (accepttok(p, TK_ASSIGN)) {
+				m.lhs = parseexpr(p);
+			};
+			if (mhead == nil) { mhead = m; mtail = m; }
+			else { mtail.next = m; mtail = m; };
+			if (!accepttok(p, TK_COMMA)) { break; };
+		};
+		expecttok(p, TK_RBRACE, "expected '}' after enum members");
+		n.list = mhead;
+		return n;
+	};
+
 	if (p.curkind == TK_VOID) {
 		// `void` keyword in type-expr context — emit as N_TNAME so
 		// resolution treats it like any other primitive name.