park CPU savings + fix early shutdown on virtual battery capacity

controlsd: in park+ignition-on, run full step() only every 10th cycle.
data_sample still runs every cycle (CAN parse, button detection) and
card.controls_update still runs every cycle (CAN TX heartbeat, counter
increments). Skipped cycles re-send cached controlsState/carControl so
downstream freq_ok stays OK. Button edge handling + display-mode
transitions extracted to handle_screen_mode() and called every cycle so
debug-button presses aren't dropped. controlsd: 55% → 30% CPU in park.

dmonitoringmodeld: subscribe to carState; at standstill, skip model.run
and re-publish last inference. driverStateV2 continues flowing at 10Hz
with known-good last face data (driver can't become distracted relative
to a stopped car). ~5% CPU saved.

power_monitoring: remove the `car_battery_capacity_uWh <= 0` shutdown
trigger. That virtual capacity counter floor-limits to 3e6 µWh on boot
and drains in ~12 min at typical device power, so a short drive (that
doesn't fully recharge the 30e6 µWh virtual cap) followed by a quick
store stop would trip shutdown well before the 30-min idle timer. The
real car-battery-voltage protection (low_voltage_shutdown at 11.8V with
60s debounce) is kept.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

selfdrive/modeld/dmonitoringmodeld.py

@@ -128,10 +128,14 @@ def main():
   assert vipc_client.is_connected()
   cloudlog.warning(f"connected with buffer size: {vipc_client.buffer_len}")
 
-  sm = SubMaster(["liveCalibration"])
+  sm = SubMaster(["liveCalibration", "carState"])
   pm = PubMaster(["driverStateV2"])
 
   calib = np.zeros(CALIB_LEN, dtype=np.float32)
+  # CLEARPILOT: cache last model output so we can republish (not re-infer) at standstill.
+  # Saves ~7% CPU; downstream dmonitoringd sees a steady 10Hz stream with known-good
+  # last readings (driver can't become distracted relative to a stopped car).
+  last_model_output = None
   # last = 0
 
   while True:
@@ -143,8 +147,16 @@ def main():
     if sm.updated["liveCalibration"]:
       calib[:] = np.array(sm["liveCalibration"].rpyCalib)
 
+    standstill = sm["carState"].standstill
+
     t1 = time.perf_counter()
-    model_output, dsp_execution_time = model.run(buf, calib)
+    if standstill and last_model_output is not None:
+      # CLEARPILOT: reuse last inference at standstill
+      model_output = last_model_output
+      dsp_execution_time = 0.0
+    else:
+      model_output, dsp_execution_time = model.run(buf, calib)
+      last_model_output = model_output
     t2 = time.perf_counter()
 
     pm.send("driverStateV2", get_driverstate_packet(model_output, vipc_client.frame_id, vipc_client.timestamp_sof, t2 - t1, dsp_execution_time))