Add interpolation toggle to set_rotation

[An0n3m0us]

Fixes: #16745
Related: luanti-org/minetest_game#3255

Add compact, short information about your PR for easier understanding:

• Goal of the PR
• How does the PR work?
• Does it resolve any reported issue?
• Does this relate to a goal in the roadmap?
• If not a bug fix, why is this PR needed? What usecases does it solve?
• If you have used an LLM/AI to help with code or assets, you must disclose this.

Adds optional interpolate parameter to set_rotation(rotation, interpolate). When false, rotation snaps instantly on the client instead of blending over ~100ms. Default true preserves existing behavior.

Needed to fix minetest_game#2950 and #2948 as the cart mod needs precise rotation timing that the engine's built-in interpolation prevents.

Kiro was used to assist with code writing of the laid out tasks plan, after investigating.

To do

This PR is a Ready for Review.

• Property added, serialized, Lua-bound, client-side respected, backward compatibility sorted
• Flag sent with AO_CMD_UPDATE_POSITION, backward compatible (extra byte, old clients ignore)
• Client reads flag and uses rot_translator.init() vs .update()

How to test

-- Snaps instantly (no client blending)
self.object:set_rotation(vector.new(math.pi/4, 0, 0), false)

-- Smooth interpolation (default, same as before)
self.object:set_rotation(vector.new(math.pi/4, 0, 0))

[appgurueu]

Thanks for taking a stab!

Regarding the implementation details: I don't think this should be a property. Properties are for "persistent"-ish values, this is a very temporary value, usually tied to a specific set_rotation() call. (Furthermore, rotation is not part of the object properties; it would be a bit odd if a property relating specifically to rotation were.)

Thus I would prefer a parameter on set_rotation(), ending up in the same AO CMD as the rotation (AO_CMD_UPDATE_POSITION, somewhat misnamed).

For a first implementation, players can be ignored; calling set_rotation() on players probably should warn anyways, it doesn't do anything reasonable because it's instantly overwritten by client-provided yaw.

Issue this PR addresses: #16745

[An0n3m0us]

hey thanks for the review, agreed, that makes a lot more sense! I've moved it from the entity level now to set_rotation instead. Updated respective minetest_game PR as well to pass in the bool on set_rotation.