test: port the xmod same-leaf collision carriers to corpus fixtures

752_modparam_callee.c -> r752_modparam_xmod_variadic_vs_scalar,
  r752_modparam_variadic_no_collision (run; alpha/beta module dirs)
784_xmod_alias_struct_collide_run.c -> r784_xmod_alias_struct_collide
  (run-exit 42), r784_xmod_alias_struct_symmetric (21),
  r784_xmod_alias_control (30) (sa/sb module dirs)
793_xmod_struct_argpush_collide_run.c -> r793_xmod_argpush_
  {recvpush_t16 107, fieldread_t16 107, combined_t16 114,
  recvpush_t12 6} (m1/m2 module dirs)
797_xmod_struct_field_layout_collide_run.c -> r797_xmod_layout_
  {ptrread_t16 107, letcopy_t16 107, addrptr_pq 10, addrval_pq 10,
  ptrwrite_t16 109, valwrite_t16 109} (m1/m2) + r797_nestfill_box (66)

r770-style sibling module dirs express the trees; the fixture corpus
runs both drivers natively (784's wwstage-build-only leg upgrades to
build+run) and test-data-byteid owns each carrier's aggregated per-
package .s compare (letcopy_t16's real discriminator). All 16 probed
green on both stages including per-package byte identity.

test/wcc/data/r752_modparam_xmod_variadic_vs_scalar/alpha/alpha.ww

@@ -0,0 +1,5 @@
+// same-leaf variadic side of the r752 collision pair.
+package alpha;
+export fn foo(a: i32, xs: i32...) i32 = {
+	return a + xs.len;
+};

test/wcc/data/r752_modparam_xmod_variadic_vs_scalar/beta/beta.ww

@@ -0,0 +1,9 @@
+// same-leaf scalar-tagged side of the r752 collision pair.
+package beta;
+export fn foo(a: i32, n: (u8 | []u8)) i32 = {
+	match (n) {
+	case let c: u8    => return a + (c: i32);
+	case let s: []u8  => return a + s.len;
+	};
+	return 0;
+};

test/wcc/data/r752_modparam_xmod_variadic_vs_scalar/case.ww

@@ -0,0 +1,11 @@
+//ww:run
+// migrated from test/wcc/752_modparam_callee.c: N_DOT callee param lookup must be module-keyed — alpha.foo variadic vs beta.foo scalar same leaf (#16).
+package main;
+import alpha;
+import beta;
+export fn main() i32 = {
+	let n: (u8 | []u8) = 7u8;
+	let r: i32 = beta.foo(10, n);
+	if (r != 17) { return 11; };
+	return 0;
+};