Add dedicated 'closed' status for listings no longer accepting applications

Distinguishes closed listings from missing apply buttons. Shows in summary
as a separate line item.

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

lib/apply/wellfound.mjs

@@ -24,7 +24,7 @@ export async function apply(page, job, formFiller) {
   }).catch(() => false);
   if (closed) {
     console.log(`    ℹ️  Job closed — no longer available`);
-    return { status: 'skipped_no_apply', meta };
+    return { status: 'closed', meta };
   }
 
   const applyBtn = page.locator('a:has-text("Apply"), button:has-text("Apply Now"), a:has-text("Apply Now")').first();