fix: recover stale named pipe from cli startup

[bestlux]

Summary

• expose named-pipe endpoint and access-denied classifiers from the shared control-plane client
• reuse those helpers in the tray startup path
• let boundlessctl --start-daemon clear stale boundlessd.exe named-pipe owners before retrying startup

Validation

• cargo fmt --all -- --check
• cargo test -p control-plane-client -p boundless-cli -p boundless-tray
• cargo clippy -p control-plane-client -p boundless-cli -p boundless-tray --all-targets -- -D warnings
• git diff --check