Fix I2C initialization for dual X3+X4 binary

Sync the runtime board profile to the detected device before I2C consumers initialize. This ensures Wire.begin() is called when needed for X3 devices. Previously, the X4 profile remained active through initialization, causing Wire to never reinitialize after detection probe, leading to X3 I2C read failures with 'could not acquire lock' errors.

lib/hal/HalGPIO.cpp

@@ -206,6 +206,18 @@ void HalGPIO::begin() {
 #if FREEINK_MCU_C3
   _deviceType = detectDeviceTypeWithFingerprint();
 
+  // Sync the runtime board profile to the detected device NOW, before any I2C
+  // consumer begins. powerManager/clock/tilt begin() run immediately after this
+  // in setup() and rely on BoardConfig::ACTIVE: HalPowerManager only calls
+  // Wire.begin() when the active profile has an I2C gauge (gaugeAddr != 0), and
+  // the X3 clock/tilt raw-Wire paths assume that begin happened. The dual X3+X4
+  // binary boots as X4 (gaugeAddr 0), so without this the X4 profile stays active
+  // through those begins, Wire is never (re)initialised after the detection probe
+  // end()s it, and every X3 read fails with lock==NULL ("could not acquire lock"
+  // / "NULL TX buffer pointer"). FreeInkDisplay also calls selectDevice() later,
+  // but that is after the I2C consumers — too late. selectDevice() is idempotent.
+  BoardConfig::selectDevice(deviceIsX3() ? BoardConfig::Board::XteinkX3 : BoardConfig::Board::XteinkX4);
+
   if (deviceIsX4()) {
     pinMode(BAT_GPIO0, INPUT);
     pinMode(UART0_RXD, INPUT);