fix: speed limit rounding, controlsd crashes, modeld calibration rate

- Speed limit display uses round() instead of floor() to fix off-by-one
- Initialize driving_gear in controlsd __init__ to prevent AttributeError
- Fix gpsLocation capnp access (attribute style, not getter methods)
- Fix sm.valid dict access (brackets not parentheses)
- modeld runs full 20fps during calibration instead of throttled 4fps
- Over-speed warning threshold below 50mph changed from 5 to 7

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

selfdrive/modeld/modeld.py

@@ -248,7 +248,8 @@ def main(demo=False):
     lat_active = sm['carControl'].latActive
     lane_changing = params_memory.get_bool("no_lat_lane_change")
     standstill = sm['carState'].standstill
-    full_rate = lat_active or lane_changing
+    calibrating = sm['liveCalibration'].calStatus != log.LiveCalibrationData.Status.calibrated
+    full_rate = lat_active or lane_changing or calibrating
 
     # Standby transitions (standstill only)
     should_standby = standstill and not full_rate