Enable BHI260AP wrist tilt wake and step counter

Wrist tilt gesture (sensor ID 67): waking the display by raising
the wrist toward you, with a light haptic click. Replaces the need
to touch the screen or press a button for the most common interaction.

Step counter (sensor ID 52): always-on pedometer displayed below
the complications on the watch face. Shows count once walking starts.

Both sensors configured after the deferred BHI260AP firmware upload
(~5s after boot). IMU events processed in the main loop via
bhi260->update(). Wrist tilt triggers display_unblank() directly.

Also added BoschSensorDataHelper.hpp for typed sensor data parsing
and imu_step_count/imu_wrist_tilt globals for cross-module access.

Gui.h

@@ -85,6 +85,7 @@ static lv_obj_t *gui_gps_value   = NULL;
 static lv_obj_t *gui_gps_label   = NULL;
 static lv_obj_t *gui_batt_value  = NULL;  // battery detail in complications
 static lv_obj_t *gui_batt_detail = NULL;
+static lv_obj_t *gui_step_label  = NULL;  // step count below complications
 
 // Radio status widgets
 static lv_obj_t *gui_radio_freq  = NULL;
@@ -140,9 +141,10 @@ static uint32_t gui_inject_until = 0;  // millis() deadline for injected touch
 // Shadow framebuffer for screenshots (RGB565 swapped / big-endian — same as display)
 uint16_t *gui_screenshot_buf = NULL;
 
-// Forward declarations — defined in Display.h / Power.h after Gui.h is included
+// Forward declarations — defined in Display.h / Power.h / .ino after Gui.h is included
 void display_unblank();
 extern float pmu_temperature;
+extern volatile uint32_t imu_step_count;
 #ifndef PMU_TEMP_MIN
 #define PMU_TEMP_MIN -30
 #endif
@@ -305,6 +307,12 @@ static void gui_create_watchface(lv_obj_t *parent) {
 
     // Rule 2
     gui_create_rule(parent, GUI_RULE2_Y);
+
+    // Step counter below complications
+    gui_step_label = gui_label(parent, &lv_font_montserrat_20, GUI_COL_DIM, "");
+    lv_obj_set_width(gui_step_label, GUI_W);
+    lv_obj_set_style_text_align(gui_step_label, LV_TEXT_ALIGN_CENTER, 0);
+    lv_obj_set_pos(gui_step_label, 0, GUI_RULE2_Y + 15);
 }
 
 // ---------------------------------------------------------------------------
@@ -532,6 +540,16 @@ static void gui_update_data() {
     }
     #endif
 
+    // Step counter
+    if (gui_step_label) {
+        if (imu_step_count > 0) {
+            lv_label_set_text_fmt(gui_step_label, "%lu steps", imu_step_count);
+            lv_obj_set_style_text_color(gui_step_label, lv_color_hex(GUI_COL_MID), 0);
+        } else {
+            lv_label_set_text(gui_step_label, "");
+        }
+    }
+
     // Battery complication — voltage and state
     if (battery_state == BATTERY_STATE_CHARGING) {
         lv_label_set_text_fmt(gui_batt_value, "%.2fV", battery_voltage);

RNode_Firmware.ino

@@ -22,12 +22,26 @@
   #include "CO5300.h"
   #include "DRV2605.h"
 
-  // BHI260AP sensor hub — IMU + GPIO expansion
+  // BHI260AP sensor hub — IMU + step counter + wrist wake
   #include <SensorBHI260AP.hpp>
+  #include <bosch/BoschSensorDataHelper.hpp>
   #define BOSCH_BHI260_GPIO
   #include <BoschFirmware.h>
   SensorBHI260AP *bhi260 = NULL;
   bool bhi260_ready = false;
+  volatile uint32_t imu_step_count = 0;
+  volatile bool imu_wrist_tilt = false;
+
+  // IMU sensor callbacks
+  void imu_step_cb(uint8_t sensor_id, uint8_t *data, uint32_t size, uint64_t *timestamp, void *user_data) {
+    if (size >= 4) {
+      imu_step_count = data[0] | (data[1] << 8) | (data[2] << 16) | (data[3] << 24);
+    }
+  }
+
+  void imu_wrist_tilt_cb(uint8_t sensor_id, uint8_t *data, uint32_t size, uint64_t *timestamp, void *user_data) {
+    imu_wrist_tilt = true;
+  }
 
   // MAX98357A I2S speaker + SPM1423 PDM microphone
   #include "Speaker.h"
@@ -2086,9 +2100,31 @@ void loop() {
       if (bhi260->begin(Wire, 0x28, I2C_SDA, I2C_SCL)) {
         bhi260_ready = true;
         pinMode(SENSOR_INT, INPUT);
+
+        // Enable wrist tilt gesture for display wake
+        bhi260->configure(SensorBHI260AP::WRIST_TILT_GESTURE, 1.0, 0);
+        bhi260->onResultEvent(SensorBHI260AP::WRIST_TILT_GESTURE, imu_wrist_tilt_cb);
+
+        // Enable step counter (low power, always-on)
+        bhi260->configure(SensorBHI260AP::STEP_COUNTER, 1.0, 0);
+        bhi260->onResultEvent(SensorBHI260AP::STEP_COUNTER, imu_step_cb);
       }
       Wire.setClock(400000UL);
     }
+
+    // Process IMU events and handle wrist wake
+    if (bhi260_ready) {
+      bhi260->update();
+      if (imu_wrist_tilt) {
+        imu_wrist_tilt = false;
+        #if HAS_DISPLAY
+          if (display_blanked) {
+            display_unblank();
+            if (drv2605_ready) drv2605_play(HAPTIC_LIGHT_CLICK);
+          }
+        #endif
+      }
+    }
   #endif
 
   if (memory_low) {