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/target_store_test.py

@@ -0,0 +1,73 @@
+"""目标隔离测试（规格 §4：track_id 优先 + 框位置最近邻、帧末老化清理）。"""
+
+from stereo_ranger import StereoConfig, TargetStore
+
+CFG = StereoConfig()  # isolation_gate_px = 50，filter_reset_frames = 5
+
+
+def test_track_key_stable_across_position_move():
+    store = TargetStore(CFG)
+    key_1 = store.resolve(0, 7, (100.0, 100.0), 1)
+    key_2 = store.resolve(0, 7, (400.0, 100.0), 2)  # 位置大幅移动仍是同一目标
+    assert key_1 == key_2
+    assert store.count == 1
+
+
+def test_nearest_neighbor_keeps_identity_within_gate():
+    store = TargetStore(CFG)
+    key_1 = store.resolve(0, None, (100.0, 100.0), 1)
+    key_2 = store.resolve(0, None, (130.0, 140.0), 2)  # 距离 50 ≤ 门限
+    assert key_1 == key_2
+
+
+def test_beyond_gate_creates_new_key():
+    store = TargetStore(CFG)
+    key_1 = store.resolve(0, None, (100.0, 100.0), 1)
+    key_2 = store.resolve(0, None, (200.0, 100.0), 2)  # 距离 100 > 门限
+    assert key_1 != key_2
+    assert store.count == 2
+
+
+def test_class_id_separates_states():
+    store = TargetStore(CFG)
+    assert store.resolve(0, None, (100.0, 100.0), 1) != store.resolve(1, None, (100.0, 100.0), 1)
+
+
+def test_two_boxes_same_frame_claim_distinct_states():
+    store = TargetStore(CFG)
+    key_1 = store.resolve(0, None, (100.0, 100.0), 1)
+    key_2 = store.resolve(0, None, (110.0, 100.0), 1)  # 同帧第二框不得接管已占用状态
+    assert key_1 != key_2
+    assert store.count == 2
+
+
+def test_state_evicted_after_reset_frames_unseen():
+    store = TargetStore(CFG)
+    key = store.resolve(0, None, (100.0, 100.0), 1)
+    store.distance_filter.advance(key, 5.0)
+    store.consistency.advance(key, 9.6)
+    for frame in range(2, 7):  # 第 2~6 帧：连续 5 帧缺席
+        store.end_frame(frame)
+    assert store.count == 0
+    assert store.distance_filter.value(key) is None
+    assert store.consistency.streak(key) == 0
+
+
+def test_present_but_invalid_keeps_position_state():
+    store = TargetStore(CFG)
+    key = store.resolve(0, None, (100.0, 100.0), 1)
+    store.distance_filter.advance(key, 5.0)
+    for frame in range(2, 8):
+        store.resolve(0, None, (100.0, 100.0), frame)  # 每帧仍出现
+        store.distance_filter.invalidate(key)
+    assert store.count == 1  # 位置状态保留
+    assert store.distance_filter.value(key) is None  # 滤波状态已按门限清空
+
+
+def test_clear_resets_everything():
+    store = TargetStore(CFG)
+    key = store.resolve(0, 5, (100.0, 100.0), 1)
+    store.distance_filter.advance(key, 5.0)
+    store.clear()
+    assert store.count == 0
+    assert store.distance_filter.value(key) is None