test(gate): clarify the 'altrove' first-token guard comment

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

harness/.pi/extensions/gate/__tests__/reserved_labels.test.js

@@ -22,7 +22,7 @@ test("canonical quit/back labels stay reserved", () => {
 test("normal merit options are NOT reserved", () => {
   assert.equal(isReserved("procedura"), false);
   assert.equal(isReserved("patologia"), false);
-  assert.equal(isReserved("altrove"), false); // starts with "altro"? no — "altrove" -> normalized "altrove" starts with "altro" -> guard below
+  assert.equal(isReserved("altrove"), false); // only the exact first token "altro" is reserved, not words that merely start with it
 });
 
 test("stripReserved drops every Altro/other variant, keeps merit order", () => {