fix: allow lexical import shadowing

test/wcc/data/paramshadowmod/pos_crossmod.ww

@@ -1,17 +1,14 @@
-// pos_crossmod — cur_mod-filtering positive. Replaces the abolished
-// pos_selfimp (self-import is hard-rejected post-#16). This module
-// (paramshadowmod) imports `shadowmod`, and the bundle also pulls module
-// `crossmod`, whose probe() has a param named `shadowmod`. crossmod does
-// NOT import shadowmod, so the shadow rule — filtered by the binding's
-// own module — must NOT trip crossmod's param, even though a sibling
-// module in the same bundle imports that leaf. Build + run; exit = 2.
+// pos_crossmod — file-local import ownership control. This source imports
+// shadowmod, while crossmod's separate source has a parameter of that name
+// and no such import. The caller's qualifier cannot leak into the sibling
+// package's lexical scope. Both stages build and run 2.
 
 package main;
 
 import shadowmod;
 import crossmod;
 
-export fn main() i32 = {
+fn main() i32 = {
 	let _ = shadowmod.say();
 	return crossmod.probe("hi");
 };