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/modeld/modeld.py

@@ -169,7 +169,7 @@ def main(demo=False):
 
   # messaging
   pm = PubMaster(["modelV2", "cameraOdometry"])
-  sm = SubMaster(["deviceState", "carState", "roadCameraState", "liveCalibration", "driverMonitoringState", "navModel", "navInstruction", "carControl", "liveTracks", "frogpilotPlan"])
+  sm = SubMaster(["deviceState", "carState", "roadCameraState", "liveCalibration", "driverMonitoringState", "navModel", "navInstruction", "carControl", "frogpilotCarControl", "liveTracks", "frogpilotPlan"])
 
   publish_state = PublishState()
   params = Params()
@@ -245,10 +245,12 @@ def main(demo=False):
     #   Full 20fps: lat requested or lane changing
     #   Reduced 4fps: not lat requested, not standstill (driving without cruise)
     #   Standby 0fps: standstill
-    # Uses LatRequested (not carControl.latActive) so modeld ramps to 20fps BEFORE
+    # Uses FPCC.latRequested (not carControl.latActive) so modeld ramps to 20fps BEFORE
     # controlsd actually engages steering — gives downstream services time to stabilize.
-    lat_active = params_memory.get_bool("LatRequested")
-    lane_changing = params_memory.get_bool("no_lat_lane_change")
+    # CLEARPILOT: both fields migrated from paramsMemory to cereal (no per-cycle file reads)
+    fpcc = sm['frogpilotCarControl']
+    lat_active = fpcc.latRequested
+    lane_changing = fpcc.noLatLaneChange
     standstill = sm['carState'].standstill
     calibrating = sm['liveCalibration'].calStatus != log.LiveCalibrationData.Status.calibrated
     full_rate = lat_active or lane_changing or calibrating