Ported Zinogre stands below the ground #10

After a cold boot in the snowy Giadrome quest, the ported Zinogre stands slightly below the ground, at ground_lift = 165.3 (ports/zinogre.toml). The Brute, with no lift, and the native Tigrex stand on it.

No floor model predicts this. mhfu-port floor (full FK, the idle clip's first frame) reads:

• the host: −1.3;
• the Brute: −1.2;
• the Zinogre: +105.0 at the lift, and −60.4 without it.

The old translation-only measure read +2.7 for all three. In game he sits about where FK puts him unlifted, as if the lift on his pelvis track never lands. The suspect is the host overlay's own handling of the hip joint; the porter pads the rig so that joint lands on the donor's hip.

• Read the port's joint heights live at idle, against the ground under him, and find what the engine does with the pelvis track's location Y: the engine's FK draws joint 0's translation and drops joint 1's, y included, and his hip height sat on joint 1
• Set the Zinogre's lift from that, or put the lift where the engine keeps it: the build carries the height onto joint 0 (travel.carry) and ground_lift is 0; lowest foot joint +13, the native Tigrex +8 to +18
• mhfu-port floor follows the engine's rule
• The Zinogre on the ground in game, by eye

Done when the Zinogre stands on the ground in game, and floor reads the host, the Brute and the Zinogre within a few units of each other.

Landed in #55 (4ec1d3d, 52651f4).