fix: restore macOS autostart launch path

[StudentWeis]

Summary

On macOS, enabling launch at system startup writes a LaunchAgent whose
ProgramArguments points at the .app bundle directory instead of the bundle
executable. launchd then attempts to execute /Applications/Ropy.app directly
and exits with EX_CONFIG, so Ropy does not start at login.

Steps to Reproduce

1. Install Ropy as /Applications/Ropy.app.
2. Enable launch at system startup in settings.
3. Inspect ~/Library/LaunchAgents/Ropy.plist.
4. Ask launchd for the loaded service state.

Expected Behavior

The LaunchAgent should launch the installed Ropy app successfully at login.

Actual Behavior

~/Library/LaunchAgents/Ropy.plist contains:

<key>ProgramArguments</key>
<array><string>/Applications/Ropy.app</string></array>

launchctl print gui/501/Ropy reports:

program = /Applications/Ropy.app
last exit code = 78: EX_CONFIG

Ropy Version

0.5.3

Operating System

macOS

Logs / Screenshots

No application log is emitted because launchd fails before starting the inner
Ropy executable.