feat(anim): idle and walk clips on the MPFB rig

Two parametric cycles authored at 30 fps instead of hand-keyed poses, so the loop
closes by construction: GigLine_Idle (60 f, breathing sway, feet planted) and
GigLine_Walk (30 f, one stride, hip 0.45 rad / knee 0.55 / arm 0.32, arms
counter-phased, torso counter-rotation).

The limb axes were measured, not assumed: a probe rotated upperleg01.L by 0.5 rad
on each axis and read foot.L, which moved -0.022 -> +0.362 in Y on X, twisted on Y
and abducted on Z. Using the wrong axis here would have produced a character
scissoring sideways, which no import error would have caught.

The character export preset now bakes animation. Without bake_anim the exporter
writes a static bind pose and Unreal imports a mesh with no AnimSequence and no
error, so the importer asserts a clip exists and prints VERDICT: PASS/FAIL.

Verified in /Game/Test/Character: Idle 1.967 s and Walk 0.967 s, both AnimSequences,
skeleton intact. Playback on a possessed pawn is not yet verified: the demo pawn has
no visible body, so that check belongs with the third-person camera item.

Tools/tests/test_fbx_export_preset.py

@@ -52,6 +52,24 @@ class CharacterPresetTest(unittest.TestCase):
         self.assertEqual(kwargs["mesh_smooth_type"], "FACE")
 
 
+class CharacterAnimationTest(unittest.TestCase):
+    """The animation flags are the difference between a clip and a silent bind pose."""
+
+    def test_bakes_animation(self):
+        kwargs = preset.preset_kwargs("ue_character_v1")
+        self.assertTrue(kwargs["bake_anim"], "without bake_anim Unreal imports no AnimSequence")
+        self.assertTrue(kwargs["bake_anim_use_all_actions"])
+        self.assertFalse(kwargs["bake_anim_use_nla_strips"])
+
+    def test_does_not_simplify_authored_keys(self):
+        kwargs = preset.preset_kwargs("ue_character_v1")
+        self.assertEqual(kwargs["bake_anim_simplify_factor"], 0.0)
+
+    def test_static_preset_stays_animation_free(self):
+        kwargs = preset.preset_kwargs("ue_metric_v1")
+        self.assertNotIn("bake_anim", kwargs)
+
+
 class OverrideTest(unittest.TestCase):
     def test_overrides_win(self):
         kwargs = preset.preset_kwargs(mesh_smooth_type="OFF")