fix(as5600): initialize prev_count_ to prevent incorrect first diff

Initialize prev_count_ to the first sensor reading in init() to avoid
calculating an incorrect diff on the first update() call. Previously,
prev_count_ defaulted to 0 while count_ was set to the actual sensor
reading, causing a large erroneous jump in the accumulator on startup.

- Set prev_count_ = count after reading initial angle
- Ensures diff calculation is correct from the first update
- Prevents accumulator corruption on initialization

Author: rahgirrafi

components/as5600/include/as5600.hpp

@@ -95,8 +95,6 @@ class As5600 : public BasePeripheral<> {
    */
   void initialize(std::error_code &ec) { init(ec); }
 
-
-
   /**
    * @brief Return whether the sensor has found absolute 0 yet.
    * @note The AS5600 (using I2C/SPI) does not need to search for absolute 0
@@ -176,8 +174,6 @@ class As5600 : public BasePeripheral<> {
     return (int)((angle_h << 6) | angle_l);
   }
 
-
-
   void update(std::error_code &ec) {
     logger_.info("update");
     std::lock_guard<std::recursive_mutex> lock(base_mutex_);
@@ -237,6 +233,7 @@ class As5600 : public BasePeripheral<> {
     std::lock_guard<std::recursive_mutex> lock(base_mutex_);
     // initialize the accumulator to have the current angle
     auto count = read_count(ec);
+    prev_count_ = count;
     if (ec) {
       return;
     }