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.

src/hal/mod.rs

@@ -7,7 +7,8 @@
     feature = "heltec_v3",
     feature = "heltec_v3_uart",
     feature = "heltec_v4",
-    feature = "elecrow_thinknode_m2"
+    feature = "elecrow_thinknode_m2",
+    feature = "lilygo_tbeam_supreme"
 ))]
 pub mod esp32s3;