fix(character): the arms hang at the sides — and why that took so long

The character now stands naturally: arms at its sides with a soft elbow bend, hands
at the hips, feet flat. Both character shots confirm it, front and back.

The root cause was not the pose. The FBX importer had been silently refusing to
replace the existing assets: after changing the arm base from 1.55 rad to 0.55 rad
and rebuilding, the imported clip returned the IDENTICAL bone quaternion
(+0.006, +0.002, -0.179, -0.984). replace_existing=True was set and delete_asset
returned False even after chmod u+w, because the pawn's constructor hard-references
the clips. Importing under a new name (CharacterV2) created fresh assets and the
same probe then returned (+0.439, +0.898) — the rotation had landed. Every earlier
attempt had been invisible for this reason.

The rotation itself is measured, not inherited: sweeping it in Blender gives 0.55 rad
for arms down and clear of the body, 0.65 for straight down against the hip, 0.75 for
past vertical and into the torso. It lives in the clamp keys, not in the bind: every
bind experiment was impossible on this shape-keyed MPFB mesh or left Unreal showing
the old bind.

Remaining, for 0.2.2: the fingers splay from the bind, and the walk clip has still
not been captured in motion.

Screenshots/README.md

@@ -106,11 +106,11 @@ Known gaps in this first pass, recorded rather than hidden:
 What this shot is evidence for:
 
 - The pawn carries a visible skeletal body with the warm skin material, and a spring-arm camera with collision testing. The **V** toggle swaps first and third person; the shipped default stays first person and the review passes `-thirdperson`.
-- **The idle clip drives the body and the arms hang at the sides.** Earlier captures of this shot showed a bind A-pose.
+- **The idle clip drives the body and the arms hang at the sides**, with the hands at the hips and the feet flat. Earlier captures of this shot showed a bind A-pose.
 
 Still open, tracked in `TODO.md`:
 
-- The arms hang close enough to clip into the torso at the shoulder, and the fingers splay slightly. That is the `0.2.2` pose-and-skin tuning pass, not this rig.
+- The fingers splay slightly, which is the bind's finger spread carried into the pose. That is the `0.2.2` pose-and-skin tuning pass, not this rig.
 - **Camera collision is implemented but unproven:** the spawn has open space behind it, so no shot exercises the arm shortening.
 
 ---
@@ -126,7 +126,7 @@ Still open, tracked in `TODO.md`:
 
 **Why the shot exists:** the third-person shot only ever shows the pawn's back, so a pose defect on the front — arms out, hands splayed, a face pointing the wrong way — was invisible in review. This angle is the check for it.
 
-What it shows: the arms hang down with a soft elbow bend and the hands sit at hip height. What it still shows wrong: the upper arms sit close enough to the torso to clip at the shoulder, and the fingers point outward-forward rather than hanging relaxed.
+What it shows: the arms hang down with a soft elbow bend, the hands sit at hip height, and the upper arms clear the torso. What it still shows wrong: the fingers are spread rather than relaxed, carried over from the bind pose.
 
 ---
 
@@ -159,7 +159,7 @@ Every issue is tracked in `TODO.md` under the version that will fix it; an issue
 | Nothing may stand in front of the hero façade that blocks it — no awning, no temporary structure | `0.9.0` → per-building models, hero façade | Open |
 | Retail parapet has no moulded profile, and wall lettering built as a plate does not read at 40 m | `0.9.0` → 6800 Lee Drug and 6806–6820, second pass | Open (moved out of `0.1.6`) |
 | 6822 Budget is a bare blockout volume — no photograph exists to model it from | `0.9.0` → photography gap | Deferred (moved out of `0.1.6`) |
-| Third-person idle pose reads awkwardly: arms hang forward and the hands splay, because the base pose is applied with inverted signs to compensate for the FBX axis flip | `0.2.2` → skin and animation tuning | Open |
+| Third-person fingers splay rather than relax — the bind's finger spread is carried into the pose | `0.2.2` → skin and animation tuning | Open |
 | Camera collision is implemented but never exercised against a wall | `0.2.0` → camera collision | Open |
 | The walk clip has never been captured in motion — it imports and its curves carry the stride, but no shot shows it | `0.2.0` → verify animation plays correctly | Open |
 | Between kerb and building line the walkable surface is the terrain mesh, not a modelled pavement | `0.6.0` → model the pavement between kerb and building line | Open |