feat(boards): LilyGo T-Beam S3 Supreme support

ESP32-S3 + SX1262 + SH1106 OLED + AXP2101 PMIC, native USB-C.

The AXP2101 PMIC gates power to the LoRa chip and the OLED. Without
its init sequence (ALDO3 = 3.3 V for LoRa, ALDO1 = 3.3 V for OLED)
the SX1262 never responds on SPI and radio init fails.

Pin map verified against MeshCore's variants/lilygo_tbeam_supreme_SX1262.
PMIC lives on a dedicated I²C1 bus (SDA=42, SCL=41) separate from the
SH1106 on I²C0 (SDA=17, SCL=18); I²C1 is used blocking for a one-shot
init and then dropped. TCXO at 1.6 V via DIO3.

New src/driver/axp.rs holds the AXP2101 init sequence — kept minimal
(only the LoRa + OLED rails), since DongLoRa is a LoRa-over-USB bridge
and every other rail (GPS, BME280, IMU, SD, batt ADC) is out of scope.

justfile

@@ -10,6 +10,7 @@ heltec_v3      := "heltec_v3 xtensa-esp32s3-none-elf esp32s3"
 heltec_v3_uart := "heltec_v3_uart xtensa-esp32s3-none-elf esp32s3"
 heltec_v4      := "heltec_v4 xtensa-esp32s3-none-elf esp32s3"
 elecrow_thinknode_m2 := "elecrow_thinknode_m2 xtensa-esp32s3-none-elf esp32s3"
+lilygo_tbeam_supreme := "lilygo_tbeam_supreme xtensa-esp32s3-none-elf esp32s3"
 rak_wisblock_4631  := "rak_wisblock_4631 thumbv7em-none-eabihf nRF52840_xxAA"
 wio_tracker_l1     := "wio_tracker_l1 thumbv7em-none-eabihf nRF52840_xxAA"
 waveshare_rp2040_lora := "waveshare_rp2040_lora thumbv6m-none-eabi rp2040"
@@ -18,7 +19,7 @@ builds_dir := "builds"
 version := `sed -n 's/^version = "\(.*\)"/\1/p' Cargo.toml`
 
 # All known boards
-boards := "heltec_v3 heltec_v3_uart heltec_v4 elecrow_thinknode_m2 rak_wisblock_4631 waveshare_rp2040_lora wio_tracker_l1"
+boards := "heltec_v3 heltec_v3_uart heltec_v4 elecrow_thinknode_m2 lilygo_tbeam_supreme rak_wisblock_4631 waveshare_rp2040_lora wio_tracker_l1"
 
 # Install all required tools and toolchains
 setup:
@@ -214,6 +215,7 @@ _info name:
      elif [ "{{name}}" == "heltec_v3_uart" ]; then echo "{{heltec_v3_uart}}"; \
      elif [ "{{name}}" == "heltec_v4" ]; then echo "{{heltec_v4}}"; \
      elif [ "{{name}}" == "elecrow_thinknode_m2" ]; then echo "{{elecrow_thinknode_m2}}"; \
+     elif [ "{{name}}" == "lilygo_tbeam_supreme" ]; then echo "{{lilygo_tbeam_supreme}}"; \
      elif [ "{{name}}" == "rak_wisblock_4631" ]; then echo "{{rak_wisblock_4631}}"; \
      elif [ "{{name}}" == "waveshare_rp2040_lora" ]; then echo "{{waveshare_rp2040_lora}}"; \
      elif [ "{{name}}" == "wio_tracker_l1" ]; then echo "{{wio_tracker_l1}}"; \