byd: spoof 508 steering feedback to camera on SEAL — fixes ADAS lockout

The Seal's camera faults (ACC + ADAS + AEB warning lights, 'unable to
activate ADAS') because panda neutralizes its intercepted 790 LKAS
commands while the camera watches the 508 feedback for execution —
seeing its requests ignored, it disables the whole ADAS suite.

The Han avoids this by echoing the camera's request back in the 792
feedback; the Seal needs the same on its 508 STEERING_TORQUE_ANGLE:

- bydcan.create_steering_torque_angle: mirrors the Han spoof logic on
  the 508 layout — when camera LKAS is active, echo its 790 torque
  request into MAIN_TORQUE and its 482 angle request into TARGET_ANGLE
  with Cruise_Activated=1; prepare -> LKSPrepare=1; passive -> neutral
- carcontroller: Seal sends the 508 spoof, Han keeps the 792 spoof
- carstate: capture the camera's 482 angle command for the spoof
- panda: whitelist 508 TX on bus 2 (absolute-limit check), stock 508
  blocked 0->2 via check_relay — one config covers both platforms
- firmware rebuilt; spoof decode-verified (camera's exact torque+angle
  echoed back); 120 safety tests + MISRA clean

NOTE: the ADAS fault latches — the car needs a full power cycle (or a
few minutes off) after flashing this build for the dash warnings to
clear.

opendbc_repo/opendbc/car/byd/carcontroller.py

@@ -30,10 +30,10 @@ class CarController(CarControllerBase):
 
     self.apply_accel_last = 0
 
-    # EPS steering feedback forwarding (792 STEERING_TORQUE) only applies to
-    # platforms whose EPS reports on 792 (HAN). The SEAL EPS reports on
-    # 508 STEERING_TORQUE_ANGLE which is forwarded stock for now.
-    self.send_steering_feedback = CP.carFingerprint != CAR.BYD_SEAL_PERFORMANCE_25
+    # EPS steering feedback is spoofed towards the camera on both platforms so
+    # the stock ADAS does not fault while its LKAS commands are intercepted:
+    # HAN uses 792 STEERING_TORQUE, SEAL uses 508 STEERING_TORQUE_ANGLE.
+    self.seal_platform = CP.carFingerprint == CAR.BYD_SEAL_PERFORMANCE_25
 
   def update(self, CC, CC_SP, CS, now_nanos):
     # car control running in 100Hz
@@ -80,12 +80,18 @@ class CarController(CarControllerBase):
                                                      lkas_request_prepare, lkas_active,
                                                      lkas_mode, CS.eps_activated)
       can_sends.append(pack)
-      if self.send_steering_feedback:
+      if self.seal_platform:
+        pack = self.can.create_steering_torque_angle(CS.eps_steering_torque_msg,
+                                                     CS.mpc_lkas_output,
+                                                     CS.mpc_lkas_request_prepare,
+                                                     CS.mpc_lkas_active,
+                                                     CS.mpc_lkas_angle_output)
+      else:
         pack = self.can.create_steering_torque(CS.eps_steering_torque_msg,
                                                CS.mpc_lkas_output,
                                                CS.mpc_lkas_request_prepare,
                                                CS.mpc_lkas_active)
-        can_sends.append(pack)
+      can_sends.append(pack)
 
       self.apply_torque_last = apply_torque