fix: thermald crash on startup — CarState is in cereal.car, not cereal.log

The new fan control plumbing referenced log.CarState.GearShifter.park,
but CarState is defined in car.capnp and only DeviceState/PandaState
live in log.capnp. Thermald crashed immediately on first carState tick,
which meant deviceState stopped publishing entirely. The UI then read
stale/default values — freeSpacePercent=0 → "100% full" → "Out of Storage"
alert despite 65 GB actually free. The fan also stopped updating.

from cereal import car, log  (was just log)
car.CarState.GearShifter.park (was log.CarState...)

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

selfdrive/thermald/thermald.py

@@ -10,7 +10,7 @@ from pathlib import Path
 import psutil
 
 import cereal.messaging as messaging
-from cereal import log
+from cereal import car, log
 from cereal.services import SERVICE_LIST
 from openpilot.common.dict_helpers import strip_deprecated_keys
 from openpilot.common.filter_simple import FirstOrderFilter
@@ -296,7 +296,7 @@ def thermald_thread(end_event, hw_queue) -> None:
       if sm.seen['carState']:
         cs = sm['carState']
         standstill = cs.standstill
-        is_parked = cs.gearShifter == log.CarState.GearShifter.park
+        is_parked = cs.gearShifter == car.CarState.GearShifter.park
       else:
         standstill = False
         is_parked = True  # default safe: assume parked, no fan floor