精简仓库结构并增强任务链路：归档双目可选后端、新增LOS判据与自定义返航

归档 legacy/：stereo_yolo/stereo_ranger/target_tracker 三包 + 175 条测试 + demo/配置/权重/三份规格；运行链路不再依赖，默认 pytest 446 条，归档测试按需运行。

目标有效性第二判据改为 LOS 运动学一致性（pod_bridge/los_consistency.py），删除 require_vision；pod_locked() 叠加该判据，状态机随之后退重搜。

自定义返航（task_runner/return_home.py）：保持转场高度回起飞点 → 恢复初始航向 → 垂直降落，不再爬 RTL_RETURN_ALT；未起飞/无起飞点/超时/异常仍退回 PX4 原生 RTL。

任务链安全兜底：主循环异常→紧急返航、stop 幂等、landing_stop 保留遥测、in_air 流复用+超时、解锁/起飞与吊舱识别仅执行一次、rtl_timeout 上限。

入口共享件拆到 utils/sitl_support.py；pod_sitl_test.py→l1_sitl_test.py；删除旧架构 test.py；相机脚本移入 tools/。

新增 .gitignore 并剔除历史误跟踪的 59 个 .pyc；requirements 按实际依赖重写；文档全面对齐，新增 legacy/README.md 与 tools/README.md。

legacy/utils/tests/stereo_ranger/consistency_test.py

@@ -0,0 +1,80 @@
+"""一致性监控测试（规格 §6.7/§11.4：N 帧降级、M 帧判 invalid、正常帧清零、每目标隔离）。"""
+
+import pytest
+
+from stereo_ranger import ConsistencyMonitor
+
+
+def _monitor() -> ConsistencyMonitor:
+    return ConsistencyMonitor(jump_px=3.0, degrade_frames=3, invalid_frames=5)
+
+
+def test_first_frame_has_no_reference_jump():
+    status = _monitor().advance("t", 10.0)
+    assert status.jump_px is None
+    assert status.abnormal is False
+    assert status.streak == 0
+
+
+def test_normal_jump_resets_streak():
+    monitor = _monitor()
+    monitor.advance("t", 10.0)
+    abnormal = monitor.advance("t", 16.0)
+    assert abnormal.abnormal and abnormal.streak == 1
+    normal = monitor.advance("t", 17.0)
+    assert not normal.abnormal and normal.streak == 0
+
+
+def test_jump_at_threshold_is_normal():
+    monitor = _monitor()
+    monitor.advance("t", 10.0)
+    assert not monitor.advance("t", 13.0).abnormal  # |ΔD| = 3.0 不超门限
+
+
+def test_degrades_at_n_frames_and_invalidates_at_m_frames():
+    monitor = _monitor()
+    monitor.advance("t", 10.0)
+    disparities = [14.0, 18.0, 22.0, 26.0, 30.0]  # 每帧跳变 4 px > 3 px
+    statuses = [monitor.advance("t", d) for d in disparities]
+    assert [s.streak for s in statuses] == [1, 2, 3, 4, 5]
+    assert [s.confidence_degraded for s in statuses] == [False, False, True, True, True]
+    assert [s.invalid for s in statuses] == [False, False, False, False, True]
+
+
+def test_targets_are_isolated():
+    monitor = _monitor()
+    monitor.advance("a", 10.0)
+    monitor.advance("b", 20.0)
+    monitor.advance("a", 15.0)  # a 跳变异常
+    assert monitor.streak("a") == 1
+    assert monitor.streak("b") == 0
+
+
+def test_drop_clears_only_target():
+    monitor = _monitor()
+    monitor.advance("a", 10.0)
+    monitor.advance("a", 20.0)
+    monitor.drop("a")
+    assert monitor.streak("a") == 0
+    assert monitor.advance("a", 40.0).jump_px is None  # 状态已清空，重新起始
+
+
+def test_clear_resets_all():
+    monitor = _monitor()
+    monitor.advance("a", 10.0)
+    monitor.advance("a", 20.0)
+    monitor.clear()
+    assert monitor.streak("a") == 0
+
+
+@pytest.mark.parametrize(
+    "kwargs",
+    [
+        {"jump_px": 0.0, "degrade_frames": 3, "invalid_frames": 5},
+        {"jump_px": 3.0, "degrade_frames": 0, "invalid_frames": 5},
+        {"jump_px": 3.0, "degrade_frames": 5, "invalid_frames": 3},
+    ],
+)
+def test_invalid_ctor_args(kwargs):
+    with pytest.raises(ValueError):
+        ConsistencyMonitor(**kwargs)