Restrict camera control to a single user during livestream sessions

[MateoLostanlen]

Our cameras are managed through the Reolink API. Currently, if two users perform levée de doute (verification) at the same time, they can both move the camera simultaneously, causing conflicts.

We need to implement a token-based control system:

Only one user can actively control a given camera at a time.

Other connected users should be in observer mode, able to view the livestream but not send control commands.

The control token should be released after a timeout or when the user explicitly ends their session.