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/README.md

@@ -51,6 +51,11 @@ Pins (`powerpod.h`):
 | UART RX | 2 |
 | LED ring | 7 |
 | BMA456 INT | 10 |
+| Button (Taster) | 12 |
+| LiPo sense 1 (ADC) | 1 |
+| LiPo sense 2 (ADC) | 12 (skipped if same as button) |
+
+> **TODO:** GPIO assignments above are provisional; confirm pinning against the real board before release.
 
 Startup order:
 
@@ -58,7 +63,8 @@ Startup order:
 2. **I2C bus** — IO expander `0x20`; optional **BMA456H** (`init_bma456`, same bus)
 3. `esp_now_comm_init(&app_config)` — WiFi + ESP-NOW
 4. `led_ring_init()`
-5. **Master only:** command queue, UART, registered commands (e.g. VERSION)
+5. `board_input_init()` — button press logs, LiPo ADC logs every **10 s**
+6. **Master only:** command queue, UART, registered commands (e.g. VERSION)
 
 ## BMA456 accelerometer (`bosch456.c`)
 
@@ -310,6 +316,7 @@ Target: ESP32-S3. Close serial monitor on the UART adapter port before running `
 | `cmd_client_info.c/h` | CLIENT_INFO handler |
 | `client_registry.c/h` | Registered slave table |
 | `bosch456.c/h` | BMA456H I2C driver, accel poll, tap INT, deadzone filter |
+| `board_input.c/h` | Taster GPIO12, LiPo ADC on GPIO1 / GPIO12 |
 | `led_ring.c/h` | LED digit display |
 | `proto/uart_messages.proto` | UART protocol schema |
 | `proto/esp_now_messages.proto` | ESP-NOW protocol schema |