Bug: Fix handling of addons from installers creating their own junction folders

As a user with addons managed by third-party installers (Aerosoft One, Contrail, etc.), I want PERFLIGHT to correctly track junction paths, So that my addon enabled/disabled states persist correctly across app restarts and rescans.

Problem Discovery

After uninstalling and reinstalling PERFLIGHT (keeping the database), all addons showed as disabled even though:

1. The junction still existed in the Community folder

2. The addon was enabled before the uninstall

Root Cause Analysis

Investigation revealed multiple issues with how link_path is set and used: