Add battery run protection: require charger below 10%

- Add bq24193_charger_connected() for charger detection
- Block install when battery < 10% and charger not plugged in
- Show clear screen after charger detected before continuing
- User can cancel with + and - to return to Hekate

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

bdk/power/bq24193.c

@@ -164,6 +164,12 @@ void bq24193_enable_charger()
 	i2c_send_byte(I2C_1, BQ24193_I2C_ADDR, BQ24193_PORConfig, reg);
 }
 
+bool bq24193_charger_connected()
+{
+	u8 status = bq24193_get_reg(BQ24193_Status);
+	return (status & BQ24193_STATUS_PG_MASK) != 0;
+}
+
 void bq24193_fake_battery_removal()
 {
 	// Disable watchdog to keep BATFET disabled.