fix(system): release keep-awake on shutdown

[kaizhou-lab]

Summary

• release system keep-awake during aioncore graceful shutdown without clearing the persisted client preference
• carry the client preference service through router runtime handles so shutdown can release the OS assertion
• cover shutdown release preserving keepAwake=true so next startup can restore it

Verification

• cargo fmt --all -- --check
• cargo test -p aionui-system
• cargo clippy -p aionui-system -p aionui-app -- -D warnings
• just push -u origin fix/keep-awake-shutdown (6920 passed, 18 skipped; nextest reported 2 slow and 2 leaky tests)