WIP H1: stiffness 1.0->50.0 / damping 0.1->5.0 diagnostic

Diagnostic probe to discriminate two hypotheses for the Newton ~10x reward
gap on Shadow-Hand-Over MAPPO at the develop pin:

- If reward jumps sharply (e.g. mean from 27 -> 100+), the actuator wiring
  works and the baseline gains were just too low; sweep for sweet spot.
- If reward stays ~27, the wiring is broken (e.g. Newton issue #2585
  imports MjcActuators as CTRL_DIRECT, fixed in PR #2598 which is 51
  commits past our pin a27277ed). Switch to IdealPDActuatorCfg or bump
  Newton.

Will revert/replace this commit once the diagnostic is interpreted.

Author: hujc7

source/isaaclab_tasks/isaaclab_tasks/direct/shadow_hand_over/shadow_hand_over_env_cfg.py

@@ -180,17 +180,21 @@ def _newton_shadow_hand_cfg(
                     "robot0_THJ(2|1)": 0.99,
                     "robot0_THJ0": 0.81,
                 },
+                # H1 sweep: stiffness 1.0 → 50.0 / damping 0.1 → 5.0 to test whether
+                # the actuator wiring is broken (Newton issue #2585) or just under-tuned.
+                # If reward jumps sharply, wiring works and base gains were just too low.
+                # If reward stays at ~27 (the baseline), wiring is broken — need PR #2598.
                 stiffness={
-                    "robot0_WRJ.*": 5.0,
-                    "robot0_(FF|MF|RF|LF|TH)J(3|2|1)": 1.0,
-                    "robot0_(LF|TH)J4": 1.0,
-                    "robot0_THJ0": 1.0,
+                    "robot0_WRJ.*": 50.0,
+                    "robot0_(FF|MF|RF|LF|TH)J(3|2|1)": 50.0,
+                    "robot0_(LF|TH)J4": 50.0,
+                    "robot0_THJ0": 50.0,
                 },
                 damping={
-                    "robot0_WRJ.*": 0.5,
-                    "robot0_(FF|MF|RF|LF|TH)J(3|2|1)": 0.1,
-                    "robot0_(LF|TH)J4": 0.1,
-                    "robot0_THJ0": 0.1,
+                    "robot0_WRJ.*": 5.0,
+                    "robot0_(FF|MF|RF|LF|TH)J(3|2|1)": 5.0,
+                    "robot0_(LF|TH)J4": 5.0,
+                    "robot0_THJ0": 5.0,
                 },
                 friction=1e-2,
                 armature=2e-3,