Body step 2.3: view rides the body, mantling and climbing work

- view follows the body (deadzone, smoothed, hard 8 cm limit); no drift over
  six held poses; hanging keeps the view on the character's head
- hold-back measured at the hips, capped leg push while held, stiffer balance
- sticky legs tuck with free-space check (fixes the mantle shove loop)
- strength asymmetric by direction; structural guide strength push-only
- limb/torso friction set before AddChild (Box3D reads it only at creation)
- new phases: pose hold, hang, human-motion mantle, hand-over-hand wall climb

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

HANDOFF.md

@@ -106,7 +106,8 @@ TERMINOLOGY (owner-corrected — use precisely):
 - **RagdollDriver.cs (step 2.2)** — `PoseFilter` (timestamps each new tracking sample, extrapolates between them in
   play-space-local space; 90 Hz tracking under 144 Hz physics otherwise feeds jerks into every feed-forward) and
   `RagdollDriver` (filter → OriginCorrection → True Body → build → Step), used by BOTH PlayerRig and RagdollSpike.
-  The 2.1 instabilities, their root causes and fixes: `research/ragdoll-player-step2.md` "Step 2.2".
+  The 2.1 instabilities, their root causes and fixes: `research/ragdoll-player-step2.md` "Step 2.2"; view
+  alignment / mantle / climbing fixes: "Step 2.3".
 - **Playground.cs** — the body sandbox around the table (east climbing/mantling, west physics toys, south
   crawl/duck/door); dynamic pieces are "prop"s reset by the menu's Reset props. `tools/playground_shots.tscn` renders
   overview PNGs (`godot-mono --path . tools/playground_shots.tscn -- <dir>`).