Fix getElementBoundingBox/radius for engineRequestModel custom models (#4925)

[QueryOfficial]

Summary

Fix getElementRadius and getElementBoundingBox for custom models created with engineRequestModel.

Custom model slots no longer share the parent model’s pColModel bounds data. After a successful DFF replace, bounds are recalculated from RenderWare atomic geometry. Visual bounds recalculation is skipped when a custom COL is applied via engineReplaceCOL.

Changes are in:

• Client/game_sa/CModelInfoSA.h
• Client/game_sa/CModelInfoSA.cpp

Motivation

Fixes #4925.

Custom models created with engineRequestModel always returned the parent model’s radius and bounding box. For object models with the default parent 1337 (trash can), scripts consistently saw the same radius and bounding box values regardless of the replaced DFF.

Root cause:

• Make*Model shallow-copied the parent CBaseModelInfoSAInterface, so the custom slot shared the parent’s pColModel
• engineReplaceModel only replaced visual geometry and did not update bounds
• getElementRadius / getElementBoundingBox read stale/shared collision bounds via CModelInfo::GetBoundingBox()

Test plan

1. Request a custom object model with engineRequestModel("object"), replace the DFF, create an object, and verify getElementRadius / getElementBoundingBox differ from parent 1337 values.
2. Repeat with an explicit parent ID (e.g. engineRequestModel("object", 1225)) and confirm returned bounds match the custom DFF, not the parent.
3. Test with custom vehicle and ped models.
4. Apply engineReplaceCOL, verify bounds come from the COL, and confirm a later DFF replace does not overwrite them.
5. Verify parent model 1337 bounds are unchanged after a custom model replace.
6. Confirm engineFreeModel does not crash or leak.
7. Replace the DFF before the model is streamed in, then verify bounds are updated after load via MakeCustomModel.

Checklist

• Your code should follow the coding guidelines.
• Smaller pull requests are easier to review. If your pull request is beefy, your pull request should be reviewable commit-by-commit.