MountVehicleOnPacker(vehicleid, packerid);

Is your feature request related to a problem? Please describe.
In SA-MP, there's currently no native way to mount a vehicle onto a Packer truck (ID 443), which makes it difficult to create realistic vehicle transport systems. Players cannot load vehicles onto the Packer without workarounds that are often buggy or visually inaccurate.

Describe the solution you'd like
I propose the addition of a native function:

MountVehicleOnPacker(vehicleid, packerid);

This function would automatically place the specified vehicle (vehicleid) on top of the specified Packer truck (packerid), using appropriate offsets and rotation values that match the Packer model. It would handle positioning, syncing, and movement so that the vehicle moves along with the truck.

An additional function to detach it would also be useful:
UnmountVehicleFromPacker(vehicleid);

Describe alternatives you've considered

• Using AttachTrailerToVehicle, but it only supports trailer-type vehicles.
• Manually updating the vehicle's position with timers, which causes desync, jittering, and performance issues.
• Using objects to fake the vehicle on top of the Packer, which is not functional and breaks immersion.

Additional context
This feature would allow better support for roleplay and trucking servers that need to simulate car delivery services, impound lots, roadside assistance, or dealership logistics. It would improve realism and expand gameplay mechanics significantly.

It is expected to behave similarly to the Cop Wheels mission from GTA: San Andreas, where the player mounts police bikes onto a moving Packer.

The issue names the proposed MountVehicleOnPacker and UnmountVehicleFromPacker entry points but provides no repository files or tests to start from. Review the existing vehicle and trailer attachment handling, then determine the native API and synchronization design needed for mounting, movement, and detachment to match the requested Packer behavior.