feat: huoyi M20 smooth/bridge training and stability docs

Current code snapshot: smooth/bridge task configs, smooth random terrain,
roll/pitch stability rewards, M20 URDF updates, eval profile and stability
training documentation.

eval_kit/__init__.py

@@ -0,0 +1,35 @@
+# Copyright (c) 2025 Deep Robotics
+# SPDX-License-Identifier: BSD 3-Clause
+
+"""可搬运的机器人性能评价套件。
+
+分层：
+
+- :mod:`eval_kit.core`      —— 零框架依赖（只用 numpy + 标准库），可整体拷到别的项目
+- :mod:`eval_kit.isaaclab`  —— IsaacLab 适配层，唯一接触仿真环境内部的地方
+- :mod:`eval_kit.profiles`  —— 机器人形态描述（加机器人 = 加一条记录）
+- :mod:`eval_kit.protocols` —— 评估协议预设
+
+命令行入口：``scripts/reinforcement_learning/rsl_rl/eval_suite.py``。
+"""
+
+from eval_kit.core.aggregation import aggregate_runs, build_upper_limit_matrix
+from eval_kit.core.metrics import compute_metrics
+from eval_kit.core.schema import EvalProtocol, RobotProfile, Trace
+from eval_kit.core.terrain_spec import get_terrain_spec
+from eval_kit.profiles import PROFILES, get_profile
+from eval_kit.protocols import PROTOCOLS, get_protocol
+
+__all__ = [
+    "EvalProtocol",
+    "PROFILES",
+    "PROTOCOLS",
+    "RobotProfile",
+    "Trace",
+    "aggregate_runs",
+    "build_upper_limit_matrix",
+    "compute_metrics",
+    "get_profile",
+    "get_protocol",
+    "get_terrain_spec",
+]