Add board input driver for button and LiPo ADC logging.

TODO: Hardware pinning in powerpod.h (TASTER_GPIO, V_LIPO_1/2_GPIO) does not
match final hardware yet — verify against schematic before production.

Co-authored-by: Cursor <cursoragent@cursor.com>

main/powerpod.c

@@ -15,6 +15,7 @@
 #include "esp_ota_ops.h"
 #include "freertos/FreeRTOS.h"
 #include "freertos/idf_additions.h"
+#include "board_input.h"
 #include "bosch456.h"
 #include "led_ring.h"
 #include "uart.h"
@@ -140,6 +141,8 @@ void app_main(void) {
 
   led_ring_init();
 
+  board_input_init();
+
   if (app_config.master) {
     cmd_queue = xQueueCreate(10, sizeof(generic_msg_t));
     init_cmdHandler(cmd_queue);