feat(variants): add Waveshare ESP32-S3-LR1121

ESP32-S3FH4R2 (4MB flash, 2MB PSRAM, native USB-CDC) with an LR1121.
Pins, the DIO5/DIO6 RF switch table and the 1.8 V TCXO follow the HF
schematic and Waveshare's examples. Envs: repeater, room server,
companion USB/BLE and KISS modem, all on min_spiffs so roles share one
partition layout.

Only RFO_HP_LF is wired (R4 on RFO_LP_LF is not fitted), so the new
opt-in LR1121_FORCE_HP_PA flag keeps RadioLib on the HP PA at <= 14 dBm,
where it would otherwise select the unconnected LP PA.

variants/waveshare_esp32s3_lr1121/WaveshareS3LR1121Board.h

@@ -0,0 +1,11 @@
+#pragma once
+
+#include <Arduino.h>
+#include <helpers/ESP32Board.h>
+
+class WaveshareS3LR1121Board : public ESP32Board {
+public:
+  const char* getManufacturerName() const override {
+    return "Waveshare ESP32-S3-LR1121";
+  }
+};