test(symlinkguard): an unremovable special file must not be reported as removed (#179)

Review round 2 on PR #190: swallowing root.Remove's error in
removeSpecial left every test green (the false 'removed' alert also named
the file). The test now asserts no message says 'removed'; red under that
flip.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ingestion/internal/symlinkguard/special_test.go

@@ -98,4 +98,7 @@ func TestWatchReportsASpecialFileItCannotRemove(t *testing.T) {
 	defer n.mu.Unlock()
 	assert.Contains(t, n.msgs[0], "ro/f.md")
 	assert.Contains(t, n.msgs[0], "special file")
+	for _, m := range n.msgs {
+		assert.NotContains(t, m, "removed", "a file it could not remove was reported as removed")
+	}
 }