fix(test): runBin trim assertion — trim shapes stream ends, not interior

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

test/helpers/run-bin.test.ts

@@ -27,7 +27,8 @@ describe('runBin', () => {
       input: 'piped|',
       trim: true,
     });
-    expect(r.stdout).toBe('piped|padded');
+    // trim shapes the ENDS of the whole stream; interior whitespace stays.
+    expect(r.stdout).toBe('piped|  padded');
     expect(r.stderr).toBe('noLANG');
   });