实现L1航向伺服(路线A1): 吊舱角度直入控制律 + 桥接胶水 + 干跑入口

- visual_track_control: ControlSnapshot 加可选 los_beta_deg/los_alpha_deg,
  第④步角度直入优先否则回退像素路径(向后兼容); config 拆出 load_from_dict 供内嵌复用
- pod_bridge: BridgeConfig 内嵌 TrackingConfig + 新 HeadingServoConfig;
  bridge._build_snapshot 合成 β/α(姿态来自PX4/角度来自吊舱,信号双路适配无电机),
  step 按 heading_servo.enabled 切 L1/L2, DEGRADED_HOLD 补发刹车保 offboard 心跳;
  run() 循环频率按生效律取(修 L1 频率错配)
- run_bridge.py: 闭环 CLI 入口, --dry-run(S2 只接吊舱不发offboard) 与实飞优雅停机
- 配置落 L1 首飞值(slow_approach/0.2mps、垂直压低、无电机仅用脱靶量)
- 新增测试 29 条(vtc5+config9+bridgeL1 10+runner5); 全量 401 passed

utils/config/pod_bridge.json

@@ -1,4 +1,6 @@
 {
+  "_comment": "吊舱↔PX4 桥接配置。heading_servo.enabled=true → 走 L1 航向伺服(TrackingControlLaw)；tracking 段为 L1 控制律参数(与 visual_track_control 同结构，各分组须齐全)。全部数值为台架标定前占位，符号(beta_sign/alpha_sign)与增益须经 S1/S2 标定后回填，标定前不得实飞。",
+
   "pod_serial": {
     "port": "",
     "baudrate": 115200
@@ -26,5 +28,60 @@
     "max_yaw_rate_dps": 30.0,
     "yaw_kp": 1.0,
     "yaw_slew_dps2": 60.0
+  },
+
+  "heading_servo": {
+    "enabled": true,
+    "beta_sign": 1,
+    "alpha_sign": 1,
+    "beta_from_frame": false,
+    "beta_from_off_target": true,
+    "alpha_from_frame": false,
+    "alpha_from_off_target": true,
+    "vertical_enabled": true,
+    "require_vision": false
+  },
+
+  "tracking": {
+    "control": {
+      "frequency_hz": 20.0,
+      "visual_stale_ms": 200,
+      "distance_stale_ms": 500,
+      "attitude_stale_ms": 300
+    },
+    "camera": {
+      "image_width": 1920,
+      "image_height": 1080,
+      "fov_h_deg": 60.0,
+      "fov_v_deg": 35.0
+    },
+    "heading": {
+      "mode": "rate",
+      "gain": 1.0,
+      "yaw_rate_limit_dps": 20.0,
+      "yaw_slew_limit_dps2": 40.0
+    },
+    "vertical": {
+      "vz_gain_mps_per_deg": 0.05,
+      "vz_limit_mps": 0.5
+    },
+    "distance": {
+      "d_exp_m": 10.0,
+      "kp": 0.5,
+      "ki": 0.0,
+      "kd": 0.0,
+      "integral_limit": 0.0,
+      "derivative_filter_coef": 0.0,
+      "approach_velocity_limit_mps": 0.5,
+      "retreat_velocity_limit_mps": 0.3,
+      "no_distance_action": "slow_approach",
+      "no_distance_approach_limit_mps": 0.2,
+      "no_distance_exit_grace_ms": 3000
+    },
+    "accel_limit": {
+      "ax_mps2": 1.0,
+      "ay_mps2": 1.0,
+      "az_mps2": 0.5
+    }
   }
 }