Add dual-firmware OTA switching and display improvements for M5Stack Unit C6L

- Add OTA partition switching via BOOT button hold during startup,
  allowing switching between repeater and companion firmware without
  reflashing. Buzzer feedback indicates switch or error.
- Fix SSD1306 64x48 display garbled output by setting correct COM pins
  configuration (0x12) after Adafruit library init, which lacks a 64x48
  case. Disable text wrap to prevent long text from overflowing.
- Fix ESP32-C6 BLE build by adding missing esp_mac.h include for
  esp_efuse_mac_get_default().
- Add display support to repeater build with C6L-specific UITask
  featuring boot screen, marquee scrolling for long node names,
  and I2C expander button wake.
- Add boot screen to companion UITask showing MeshCore version and
  mode, with marquee scrolling and unread message count.
- Reorganize variant UITask files into companion/ and repeater/
  subdirectories for consistency.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: TheRealHaoLiu

src/helpers/esp32/SerialBLEInterface.cpp

@@ -1,4 +1,5 @@
 #include "SerialBLEInterface.h"
+#include <esp_mac.h>
 
 // See the following for generating UUIDs:
 // https://www.uuidgenerator.net/

src/helpers/ui/SSD1306SPIDisplay.cpp

@@ -31,6 +31,17 @@ bool SSD1306SPIDisplay::lazyInit() {
     return false;
   }
   Serial.println("SSD1306: display.begin() OK");
+
+  // Fix for 64x48 displays: Adafruit library lacks this case and defaults
+  // to comPins=0x02 (sequential). Displays taller than 32px need 0x12
+  // (alternative COM pin config) or the output is garbled.
+  #if defined(DISPLAY_WIDTH) && defined(DISPLAY_HEIGHT)
+  #if (DISPLAY_WIDTH == 64) && (DISPLAY_HEIGHT == 48)
+  display.ssd1306_command(SSD1306_SETCOMPINS);
+  display.ssd1306_command(0x12);
+  #endif
+  #endif
+
   // Clear any garbage in the display buffer
   display.clearDisplay();
   display.display();
@@ -63,6 +74,7 @@ void SSD1306SPIDisplay::startFrame(Color bkg) {
   display.setTextColor(_color);
   display.setFont(NULL);  // Default 6x8 font
   display.setTextSize(1);
+  display.setTextWrap(false);
   display.cp437(true);
 }
 

variants/m5stack_unit_c6l/M5StackUnitC6LBoard.h

@@ -2,6 +2,7 @@
 
 #include <Arduino.h>
 #include <Wire.h>
+#include <esp_ota_ops.h>
 #include <helpers/ESP32Board.h>
 
 // PI4IO I/O Expander (I2C address 0x43)
@@ -44,6 +45,52 @@ class M5StackUnitC6LBoard : public ESP32Board {
     return true;
   }
 
+  void checkOTASwitch() {
+    // If BOOT button (P0) is held during startup, switch to the other OTA partition
+    if (!isButtonPressed()) return;
+
+    // Button is pressed — wait a moment and confirm it's still held
+    delay(500);
+    if (!isButtonPressed()) return;
+
+    const esp_partition_t* running = esp_ota_get_running_partition();
+    const esp_partition_t* next = esp_ota_get_next_update_partition(running);
+    if (next == NULL) {
+      Serial.println("OTA switch: no other partition found");
+      return;
+    }
+
+    // Verify the other partition has valid firmware
+    esp_app_desc_t app_desc;
+    if (esp_ota_get_partition_description(next, &app_desc) != ESP_OK) {
+      Serial.println("OTA switch: other partition has no valid firmware");
+#ifdef PIN_BUZZER
+      // Error buzzer: three short beeps
+      for (int i = 0; i < 3; i++) {
+        tone(PIN_BUZZER, 200, 100);
+        delay(200);
+      }
+      noTone(PIN_BUZZER);
+#endif
+      return;
+    }
+
+    Serial.printf("OTA switch: %s -> %s\n", running->label, next->label);
+
+#ifdef PIN_BUZZER
+    // Confirmation buzzer: ascending two-tone
+    tone(PIN_BUZZER, 1000, 150);
+    delay(200);
+    tone(PIN_BUZZER, 1500, 150);
+    delay(200);
+    noTone(PIN_BUZZER);
+#endif
+
+    esp_ota_set_boot_partition(next);
+    delay(200);
+    ESP.restart();
+  }
+
   void initIOExpander() {
     // Initialize PI4IO I/O expander for LoRa control pins
     // P5: LNA Enable, P6: RF Switch, P7: LoRa Reset
@@ -105,6 +152,9 @@ class M5StackUnitC6LBoard : public ESP32Board {
     pinMode(PIN_BUZZER, OUTPUT);
     digitalWrite(PIN_BUZZER, LOW);
 #endif
+
+    // Check if BOOT button is held to switch firmware
+    checkOTASwitch();
   }
 
   const char* getManufacturerName() const override {