fix(harmonyos): clear expired device roster and refine signed-out connect UX

[wgqqqqq]

Summary

• clear the published peer-device roster immediately when account authentication expires, preventing signed-out phones from showing stale devices
• expose both QR pairing and BitFun account login while signed out
• keep the empty device section minimal with a plus action that opens the login-or-scan chooser
• stack the scan and account-login actions vertically without explanatory copy

Verification

• pnpm run harmony:architecture
• HarmonyOS local unit tests
• HarmonyOS debug HAP build
• installed and exercised on real HarmonyOS device 5ZU0226202001116
• verified signed-out empty roster, QR/login entry points, plus chooser, and Back behavior

Remote scenarios

• Peer Device Mode: exercised the signed-out controller state and connection entry points on a real HarmonyOS device
• Remote workspace, remote control relay, and detached dispatch: not changed or exercised