fix: allow lexical import shadowing

test/wcc/data/paramshadowmod/neg_param.ww

@@ -1,8 +1,8 @@
-// neg_param — fn param `shadowmod: str` shadows the imported module.
-// Under the "value names and module names are disjoint" rule the
-// build must fail with a clear diagnostic at the param decl site.
+// Legacy neg_param, now a positive lexical-scope case. The package selector
+// in main uses the file-scope import; the parameter named shadowmod is a
+// closer binding only inside probe. Builds and runs 42 + len("hi") = 44.
 
-package paramshadowmod;
+package main;
 
 import shadowmod;
 
@@ -10,6 +10,6 @@ fn probe(shadowmod: str) i32 = {
 	return shadowmod.len;
 };
 
-export fn main() i32 = {
-	return probe("hi");
+fn main() i32 = {
+	return shadowmod.say() + probe("hi");
 };