ffi M1.0 (2/3, xfail): '=>' body inside '#objc_class' member

parseForeignClassDecl ([src/parser.zig:1262]) accepts ';'
(declaration) or '{ ... }' (block body) but not '=>' for member
methods. The arrow form, which parseFnDecl ([src/parser.zig:1647])
already handles for top-level/struct decls (M1.0 1/3), surfaces
'expected ;' at the arrow today.

Snapshot pins that error so the next commit (the parser
extension) shows up as a single diagnostic→runtime-output diff
in 140-expression-bodied-objc-method.{txt,exit}.

examples/140-expression-bodied-objc-method.sx

@@ -0,0 +1,20 @@
+// M1.0 (xfail) — '=>' expression-body form inside '#objc_class'
+// member methods.
+//
+// Today: parseForeignClassDecl ([src/parser.zig:1262]) accepts ';'
+// (declaration) or '{ ... }' (block body) but not '=>'. Trying
+// '=>' surfaces 'expected ;' at the arrow.
+//
+// Next commit extends the member parser to accept the arrow
+// form, mirroring the existing parseFnDecl ('=>') arm, and this
+// snapshot flips from a parser error to '42\n'.
+
+#import "modules/std.sx";
+
+SxFoo :: #objc_class("SxFoo") {
+    greet :: (self: *Self) -> s32 => 42;
+}
+
+main :: () -> s32 {
+    0;
+}

tests/expected/140-expression-bodied-objc-method.exit

@@ -0,0 +1 @@
+1

tests/expected/140-expression-bodied-objc-method.txt

@@ -0,0 +1 @@
+/Users/agra/projects/sx/examples/140-expression-bodied-objc-method.sx:15:35: error: expected ';'