Fix abbreviateNumber result.trim() return value not assigned back

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/unit/module/abbreviateNumber.test.js

@@ -43,4 +43,9 @@ describe('abbreviateNumber', () => {
   it('handles NaN input', () => {
     expect(abbreviateNumber('abc').trim()).toBe('');
   });
+
+  it('does not have trailing whitespace', () => {
+    expect(abbreviateNumber(45)).toBe('45s');
+    expect(abbreviateNumber(3661)).toBe('1h 1m 1s');
+  });
 });