Add Proximity Alert

Add a function where car can activate lights when someone approaches vehicle.

Need some smart logic and state logic for this.
- only when in park mode for a certain amount of time
- never trigger when any door is open
- never trigger on anyone who previously occupied the vehicle in any seat
- maybe only trigger when approached from side and rear?
- things like this, basically a way to make sure its not constantly firing

Can trigger siren if easy? Not sure if LVC would have to be involved here.

Config setup method undecided.

No files, tests, or entry points are named. Start by mapping the existing vehicle state and configuration paths, then resolve the park-time, door, prior-occupant, approach-direction, siren, and LVC decisions. Done means the alert behavior and configuration are explicitly specified and validated against those cases.

Written by the indexing model from the issue text.