fix: release GPIO13 hold before re-entering deep sleep

gpio_hold_en(GPIO13) called in startDeepSleep() persists after wake when
keepClockAlive=true. A subsequent startDeepSleep() call (e.g. failed button
verification) would silently fail to change GPIO13's level, leaving the MOSFET
latched and trapping the device in a sleep/wake loop requiring a hardware reset.

Release the individual and global holds at the top of startDeepSleep() so each
sleep entry configures GPIO13 from a clean state. Also call
gpio_deep_sleep_hold_dis() immediately after wake in setup() as a defensive
measure.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/main.cpp

@@ -236,6 +236,7 @@ void setup() {
   HalSystem::begin();
   gpio.begin();
   powerManager.begin();
+  gpio_deep_sleep_hold_dis();  // Release deep sleep GPIO hold state from previous sleep cycle
 
   // Only start serial if USB connected
   if (gpio.isUsbConnected()) {