feat: 4Hz fan control with gear/cruise-aware clamps; move hot signals to cereal

Fan control rework (thermald → 4Hz):
- DT_TRML 0.5s → 0.25s (thermald loop + fan PID now at 4Hz)
- New clamp rules based on (gear, cruise_engaged, standstill):
    parked                                → 0-100%
    in drive + cruise engaged (any speed) → 30-100%
    in drive + cruise off + standstill    → 10-100%
    in drive + cruise off + moving        → 30-100%
- thermald now reads gearShifter (via carState) and controlsState.enabled,
  passes them to fan_controller.update()
- Removed BENCH_MODE special case — new rules cover bench automatically
- Removed ignition-based branches — gear is the correct signal

System health overlay:
- Subscribed UI to peripheralState so we can read fanSpeedRpm
- Added FAN row: actual fan% (RPM / 65) to sit alongside LAG/DROP/TEMP/CPU/MEM.
  Shows the real fan output vs. what the PID is asking for.

Migrate hot signals from paramsMemory to cereal (frogpilotCarControl):
- Added latRequested @3 and noLatLaneChange @4 to FrogPilotCarControl schema
- controlsd sets FPCC.latRequested / FPCC.noLatLaneChange (send-on-change
  already gates the IPC)
- modeld reads from sm['frogpilotCarControl'] (added to its subscribers)
  instead of paramsMemory (saves ~20 file-read syscalls/sec)
- carcontroller reads from frogpilot_variables (set in-process by controlsd)
  instead of paramsMemory (saves ~100 file-read syscalls/sec in 100Hz path).
  Dropped carcontroller's now-unused Params instance and import.
- UI (ui.cc, onroad.cc) reads from sm['frogpilotCarControl'].noLatLaneChange
- Removed LatRequested and no_lat_lane_change param registrations + defaults

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

selfdrive/car/hyundai/carcontroller.py

@@ -8,7 +8,6 @@ from openpilot.selfdrive.car.hyundai import hyundaicanfd, hyundaican
 from openpilot.selfdrive.car.hyundai.hyundaicanfd import CanBus
 from openpilot.selfdrive.car.hyundai.values import HyundaiFlags, Buttons, CarControllerParams, CANFD_CAR, CAR
 from openpilot.selfdrive.car.interfaces import CarControllerBase
-from openpilot.common.params import Params
 VisualAlert = car.CarControl.HUDControl.VisualAlert
 LongCtrlState = car.CarControl.Actuators.LongControlState
 
@@ -57,9 +56,6 @@ class CarController(CarControllerBase):
     self.car_fingerprint = CP.carFingerprint
     self.last_button_frame = 0
 
-    # CLEARPILOT: cache Params instance — create_steering_messages was building
-    # a new one every 10ms (100Hz), causing needless allocation + file opens
-    self.params_memory = Params("/dev/shm/params")
 
   def update(self, CC, CS, now_nanos, frogpilot_variables):
     actuators = CC.actuators
@@ -116,7 +112,8 @@ class CarController(CarControllerBase):
       hda2_long = hda2 and self.CP.openpilotLongitudinalControl
 
       # steering control
-      no_lat_lane_change = self.params_memory.get_int("no_lat_lane_change", 1)
+      # CLEARPILOT: no_lat_lane_change comes via frogpilot_variables (set by controlsd in-process)
+      no_lat_lane_change = int(getattr(frogpilot_variables, 'no_lat_lane_change', False))
       can_sends.extend(hyundaicanfd.create_steering_messages(self.packer, self.CP, self.CAN, CC.enabled, apply_steer_req, apply_steer, no_lat_lane_change))
 
       # prevent LFA from activating on HDA2 by sending "no lane lines detected" to ADAS ECU