[PanthPtl2005]

Problem

Installing the TetherKit privileged helper can fail when the
LaunchDaemon plist has the com.apple.quarantine extended attribute.

The failure appears as:

Bootstrap failed: 5: Input/output error

The macOS launchd log reports:

Refusing to execute/trust quarantined program/file

Fix

Remove the com.apple.quarantine attribute from the installed
LaunchDaemon plist before registering the service with launchctl.

The removal is limited to the quarantine attribute and does not
remove other extended attributes.

Testing

Reproduced the issue from a clean checkout on Apple Silicon/macOS 27.

Before the fix:

Bootstrap failed: 5: Input/output error

After the fix:

==> 完成。TetherKit.app 会自动检测到它，不需要重启 App。

Verified with:

sudo launchctl print system/com.tetherkit.helper

The helper reports:

state = running
initialized = 1
last exit code = (never exited)

Also verified that the installed LaunchDaemon plist no longer contains
com.apple.quarantine.