test(install-targets): add positive rules assertion to claude-project foreign-path test

Addresses CodeRabbit review: the negative-only assertions could have
passed on an empty plan. Add a positive assertion that the non-foreign
'rules' path is still planned under .claude/rules/ecc so regression to
zero ops would fail loudly.

tests/lib/install-targets.test.js

@@ -943,6 +943,13 @@ function runTests() {
       ],
     });
 
+    assert.ok(
+      plan.operations.some(operation => (
+        normalizedRelativePath(operation.sourceRelativePath) === 'rules'
+        && operation.destinationPath === path.join(projectRoot, '.claude', 'rules', 'ecc')
+      )),
+      'Should still include non-foreign rules path (guards against empty-plan regression)'
+    );
     assert.ok(
       !plan.operations.some(operation => (
         normalizedRelativePath(operation.sourceRelativePath) === '.cursor'