fixup! diigo-cache: RSS in diigo's export shape, from cached items

compare-export.ts runs main only under import.meta.main (Node's
`if __name__ == "__main__"`), so importing it — say, from a test —
runs nothing.

Generated-by: Claude Opus 5.5

diigo-cache/scripts/compare-export.ts

@@ -154,4 +154,5 @@ export function main(
 	exit(0);
 }
 
-main();
+// run only as a program, not when imported (e.g. by a test)
+if (import.meta.main) main();