fix(walk): the cycle starts at maximum stride, so the capture shows one

The stride shot regressed twice for two different reasons, and only the second was
the clip. The walk cycle was authored on a sine, which is zero at both the start and
the middle of the cycle - exactly the two frames where the legs pass together - so a
deterministic capture at any phase near those frames read as a still. The probe
proved it: frames 0 and 15 carried identical hip rotations while 7 and 22 were the
stride.

The cycle now starts at maximum stride (cosine). Length, amplitudes, keys and loop
are unchanged; only the phase moved. demo-third-person-walk is back as shot 8 and
shows a genuine stride with the curled hands from 0.2.1.

8/8 shots verify.

TODO.md

@@ -11,7 +11,9 @@ Actionable task list for this project. This file is the single, central place fo
 
 ## 0.2.2 — Skin and hair tuning (patch)
 
-### Patch tasks
+### Patch tasks - active - session-5598ce7e-27e3-4c64-bb49-c04a4a31ee58 (branch `anim-body-0.2.0`)
+
+- [x] Restore the stride capture after the pose rewrite. The walk cycle started on a **sine**, zero at both the start and the middle of the cycle, so the deterministic capture kept landing on the two passing frames where the legs are together. Starting the cycle at maximum stride (cosine) fixed it with no other change; `demo-third-person-walk` is back as shot 8 and shows a genuine stride.
 
 - [ ] Tune skin shading and hair materials on the player character.
 - [ ] Tag `v0.2.2` and write `CHANGELOG.md` entry; then remove this section.