fix: allow lexical import shadowing

test/wcc/data/paramshadowmod/pos_rename.ww

@@ -1,6 +1,5 @@
-// pos_rename — positive case. The fn param is renamed away from the
-// imported module's bareword, so the rule doesn't fire and the body
-// can call `shadowmod.say()` cleanly. Built + run; exit code = 42.
+// pos_rename — control with an unrelated parameter name. The file-scope
+// import remains visible in probe. Both stages build and run 42.
 
 package main;
 
@@ -11,6 +10,6 @@ fn probe(s: str) i32 = {
 	return shadowmod.say();
 };
 
-export fn main() i32 = {
+fn main() i32 = {
 	return probe("hi");
 };