Add G20 calibration assets, L20 compare, and refresh README.

Sync calibrated G20 URDF/MJCF/JSON lookup, L20 V10.1 dual-compare scripts,
joint GUI, and document O6/G20/L20 startup on the Gitea repo.

Co-authored-by: Cursor <cursoragent@cursor.com>

run_dual_mujoco_compare.sh

@@ -0,0 +1,62 @@
+#!/usr/bin/env bash
+# 同时开两个 MuJoCo：当前标定 G20 + L20 V10.1 原版 URDF
+# 共用同一条 0~255 控制话题（默认 /g20/cb_left_hand_control_cmd）
+#
+# 用法:
+#   ./run_dual_mujoco_compare.sh
+#   ./run_dual_mujoco_compare.sh --cmd-topic /cb_left_hand_control_cmd
+#   ./run_dual_mujoco_compare.sh --speed 1.0
+set -eo pipefail
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+cd "$ROOT"
+
+PKG_SRC="$ROOT/src/linkerhand-sim/linker_hand_mujoco_ros2/linker_hand_mujoco_ros2"
+G20_XML="$PKG_SRC/urdf/G20/linker_hand_g20_left/linker_hand_g20_left.xml"
+L20_XML="$PKG_SRC/urdf/L20_V10.1/linker_hand_l20v101_left/linker_hand_l20v101_left.xml"
+
+if [[ ! -f "$G20_XML" ]]; then
+  echo "[error] missing G20 MJCF: $G20_XML" >&2
+  exit 1
+fi
+if [[ ! -f "$L20_XML" ]]; then
+  echo "[error] missing L20 MJCF: $L20_XML" >&2
+  exit 1
+fi
+
+EXTRA=("$@")
+
+cleanup() {
+  [[ -n "${PID_G20:-}" ]] && kill "$PID_G20" 2>/dev/null || true
+  [[ -n "${PID_L20:-}" ]] && kill "$PID_L20" 2>/dev/null || true
+}
+trap cleanup EXIT INT TERM
+
+echo "[dual] G20 calibrated  xml=$G20_XML"
+"$ROOT/run_g20_mujoco_plan.sh" \
+  --xml "$G20_XML" \
+  --node-name g20_calibrated \
+  --window-title "G20 calibrated (current)" \
+  --sim-state-topic /sim/mujoco/g20/left/joint_state \
+  --mapping g20_calibrated \
+  "${EXTRA[@]}" &
+PID_G20=$!
+
+# 错开一点，避免两个 GLFW 同时抢显示
+sleep 1
+
+echo "[dual] L20 V10.1 stock xml=$L20_XML (URDF-native mapping, no G20 corrections)"
+# L20 mesh 弯曲时自碰多，默认 collision_project 会把运动全部打回；对比时关闭。
+"$ROOT/run_g20_mujoco_plan.sh" \
+  --xml "$L20_XML" \
+  --node-name l20v101_stock \
+  --window-title "L20 V10.1 stock (URDF only)" \
+  --sim-state-topic /sim/mujoco/l20v101/left/joint_state \
+  --mapping l20_urdf \
+  --no-collision-project \
+  "${EXTRA[@]}" &
+PID_L20=$!
+
+echo "[dual] both started. same cmd topic (default /g20/cb_left_hand_control_cmd)."
+echo "[dual] L20: collision_project=off (mesh self-overlap would freeze motion)."
+echo "[dual] Ctrl+C stops both."
+wait "$PID_G20" "$PID_L20"