Cross-monitor event media authorization bypass in direct event media endpoints

ZoneMinder is a free, open source closed-circuit television software application. Versions prior to 1.36.39, 1.38.4, and 1.39.11 allow an authenticated low-privileged user with coarse `Events=View` and/or `Snapshots=View` permissions to directly fetch media for events belonging to monitors they are not allowed to access. The normal UI correctly hides the restricted monitor and its events, but direct event media views accept an arbitrary `eid` and stream media from the event path without enforcing the event/monitor-level ACL. This exposes private surveillance footage across monitor boundaries. Versions 1.36.39, 1.38.4, and 1.39.11 fix the issue.