w6c+selfhost: same-module preference for bare-leaf lookup

test/wcc/data/samemodprefer/pos.ww

@@ -0,0 +1,20 @@
+// Positive case: two modules each export `read` with DIFFERENT
+// signatures (mod1: i32 → i32, mod2: str → i32). Each module also
+// exports a `caller` that invokes bare `read(...)` with its own arg
+// type. The bare-leaf inside mod1 must bind to mod1.read; inside mod2
+// to mod2.read. If preference doesn't kick in and the bare lookup
+// picks the other module's `read`, the build fails with a signature
+// mismatch at check-time. The driver test asserts that this fixture
+// builds successfully.
+//
+// We don't assert runtime exit codes here because cgen still emits
+// unmangled `TEXT read` labels for both modules and the linker
+// collapses them — that's a separate codegen sweep, orthogonal to the
+// resolver fix this test pins.
+
+use mod1;
+use mod2;
+
+fn main() i32 = {
+	return 0i32;
+};