v2.8.1-rc4

Changelog

• 025d9d4 fix(postage): resume live sync where snapshot replay stopped (#5517)
• 5c739d1 feat(node): use postage snapshot on --resync unless skipped (#5519)
• 5441f28 fix: stamper store was dirty (#5515)
• e9b6987 fix: nested config priority (#5514)
• 3b1fc52 fix(api): guard nil postage contract in /chainstate during startup (#5511)
• 8e9a606 chore(redundancy): increment fetchedCnt before closing wait channel (#5505)
• f5d0b4b fix(api): reject empty label on PATCH /stamps/{batch_id} (#5512)
• c02dbde ci: auto-assign PR author when none is set (#5507)