The old approach used memcpy to copy PID_Init_Config_s into PIDInstance,
relying on identical struct layout at the beginning. This is fragile and
confusing. Now assigns each field explicitly.
UpdateCount was only used as a first-time-initialization flag for the
accel low-pass filter, not as a real counter. Replaced with a simple
uint8_t flag and moved the set to the first-update path.